I just linked mine recently and what it wants is for you to enter just your username in the first field to link accounts. The service URL should be "bsky.social" without the quotes.

The last part took me a minute to figure out but you have to go into the Bluesky settings, Privacy and Security, then App Passwords to generate a password.

Boomer let me know if something I said wasn't quite right, I'm recalling by memory on how I did it since I can't look at it again without disconnecting.

probs worth asking BlueSky support rather than on here tbh..