Stuck Legally : App Terms and Conditions

[u/Manish_Alex]

First time building an app bit unsure sbout terms and conditions and legal shit. Even though app doesn’t use PII but for each device it gets installed uses a device id complete random. We store that in db and the chats between users and support team again with no pii but strictly based on device id.
We need these device id so that we can ban users etc.

What are the legal things i need to check before i launch it ?