Help! I can't open existing file

Help!
When I try to open an existing file, I get a message saying I need to sign in. When I click “Sign In” nothing happens, even though I am signed in to Trimble in Safari.

Any tips on what is going on?
Thanks

Close SketchUp,
then delete the login_session.dat file in the user library:

https://support.sketchup.com/s/article/Log-in-errors

Problem solved.
Thank you very much.