Hello User2590,
Welcome to Microsoft Q&A forum.
Regarding your questions about linking your device. Yes, it is generally safe for you to sign in with your account and link your device. It shouldn't block your sign in by any means. Delays may occurs, so if you don't see it right away, it doesn't means that something is broken.
Before we proceed with your stale sign in, may I have a photo of the situation to check for you? Please remember to remove all personal information before posting.
I'm waiting for your reply.