• Does this work with my lock / What lock should I use?
  

This works with any lock that supports remote programming. ZigBee and Z-Wave/Plus locks (WiFi locks are NOT supported) from Yale (YRD256, YRD240, YRD226, YRD216, YRD220, YRD210, YRL256, YRL226, YRL220, YRL216, B1L, T1L), Schlage (FE469, BE469, FE599, JFE109), Kwikset (Obsidian, 916, 914, 912, 910, 888, 620), Ultraloq (U-Bolt, U-Bolt Pro), IDLock, KeyWe, Samsung etc generally support remote programming. You can see this post to compare lock features.

• Can I use the stock/default ST Z-Wave/ZigBee Device Handler for my lock with this SmartApp or do I need a custom Device Handler?
  

Yes you can use the stock ST Z-Wave Lock/ZigBee Lock device handler. Using the Enhanced Universal Z-Wave Lock device handler you can get access to some advanced features like Invalid Code notifications and many other features.
 

• Can I control multiple locks with the app?
  

Yes you can control multiple locks from a single app instance. Select all locks on the main page and then you can assign locks to individual users in the Manage Users page. 
 

• Can I install the app multiple times to control different locks?
  

Yes you can install the app as many times as you like. Each app can control one or more locks. However make sure that one lock is NOT controlled by more than one app. i.e. A single app can program two locks but two apps cannot control the same lock or they will conflict with each other.
 

• Can LUM import my existing lock codes?
  

No, when you install LUM you should clear all codes (see Clear Codes Procedure) to avoid a conflict and then only program codes through LUM.

• Can I program codes directly on the lock?
  

No, you should only program codes through LUM to avoid any conflicts.

• My property is in a different timezone from where I live, when I move there and I open the ST app, the start/end times for codes have changed 
  

SmartThings mobile app adjusts for timezone differences while displaying the time when your mobile phone changes location. So if you moved from California to Texas, the phone would add +2 hrs to the time while displaying it. You don’t need to worry as the time is translated automatically by the hub. When setting the start/end time of the codes, you will be selecting the time to be used where your hub is located. Once you click Done, the SmartThings mobile app will show you the equivalent local time on your phone. E.g. If your phone is in EST timezone and your hub in PST timezone, you set the time to 2:30pm (hub time), after you click Done it will show 5:30pm (equivalent mobile phone local time) on your mobile phone.

• Does my mobile phone need to be open all the time for the scheduling and user management to work?

The SmartApp runs in the SmartThings cloud. As long as your hub is connected to the internet, the app will automatically download the latest schedules from your reservation calendars about once every 30 minutes and keep the users on your locks updated, even if the mobile phone is turned off.

• If my internet connection is disconnected will my lock user codes stop working?

The programmed user codes in the lock will continue to work even if the internet is disconnected. However any new users or removal of expired users will not take place until the internet connection is restored.

The color indicates the current state of the user:

• Green means the user is active (confirmed by the lock)
  
• Grey means the user is inactive/expired/deleted (confirmed by the lock)
  
• Yellow means the programming request has been sent and the app is awaiting confirmation from the lock
  
• Red means the lock is not responding to programming requests and may indicate problems with the lock/mesh
  

The Sure Programming Engine will retry code programming (configurable in advanced settings) on a failure/no response from the lock. Extended yellow and red statuses indicate that the lock is having trouble communicating with the mesh. Ensure that the lock is no further than about 20ft from the nearest buffering repeater (Z-Wave or ZigBee). You need atleast 1 buffering device between the hub and the lock (even if you hub is just a few feet from the lock). A buffering device is any mains powered device like a switch or an outlet. E.g. You can pair and place a Z-Wave Plus outlet between the hub and the lock. You can find more details here.

• I'm constantly seeing "Added user in door" followed by "Deleted user in door"
  

This means there is more than one instance of LUM or another User Management SmartApp controlling the same lock. One SmartApp is adding the user while the other is deleting it and they are stuck in a loop.

Delete the other SmartApps. Each lock should only have one SmartApp programming users to avoid conflicts. You can verify this on your SmartThings app by clicking on Automations -> Expand the SmartApps section and ensure that only one instance of the RLA app is installed. Uninstall all other instances or User Management SmartApps.

• I see the app try to set/delete the same code repeatedly or I'm having difficulty controlling my lock
  

The Sure Programming Engine is built to handle adverse conditions and verify code programming. Retrying the same programming action multiple times means that the app isn't receiving a response from the lock. Try replacing the lock batteries and for best performance ensure that the lock is no further than about 20ft from the nearest buffering repeater (Z-Wave or ZigBee). You need atleast 1 buffering device between the hub and the lock (even if you hub is just a few feet from the lock). This is required to make and maintain a strong/reliable mesh and accounts for most issues. A buffering device is any mains powered device like a switch or an outlet. E.g. You can pair and place a Z-Wave Plus outlet between the hub and the lock. You can find more details here.

• How do I delete a User?
  

Open the LUM app, click on Manage Users -> Click on the user -> Delete the code -> Delete the name -> Tap Next

• Can I install LUM and RLA (Rental Lock Automater) on the same lock?
  

You can only install one app at a time on a lock, either LUM or RLA, otherwise they will conflict with each other.

• How do I clear users programmed through LUM ?
  

Open the app, set the Users to 0 -> Tap Done and wait for about 5 minutes.