Hello @remoteUser1 ,
RemoteApp services requires a Active Directory Domain Services environment to work if you are trying to deploy it in an on-premise windows server setting. You need a local domain controller where our user's will reside. RemoteApp is a part of Remote Desktop Services server infrastructure does not provide any specific way to auto create the users . You would need to create all the users manually or using some script within the Active Directory domain where you have joined the Remoteapp server.
If you are setting it up on the Azure Cloud , then you can use the Windows virtual desktop host pools to get same kind of remoteApp experience for your users and have users from your Azure Active directory (synced with on-prem AD) use the remote app. Here you have another option to setup Azure AD domain Services and join the WVD hosts to the Azure AD domain services managed domain which will again use the existing users in the Azure AD domain services instance.
All in all users do not get created automatically by the system and you would have to manually create them or automate the task using any script in order to get 30 users created in the backend system supporting RemoteApp infrastructure. I have tried to explain all the possible scenarios as it was not mentioned that what is the backend environment for Remoteapp setup . I have provided some links which are related and would encourage you to go through them. If the information provided is useful , please do accept the same as answer so that it benefits others in the community searching for similar answers. In case you have any additional queries on this , please let us know and we will be happy to help further.
Thank you.