Hi @yashar, thanks for the post and sorry to hear that you are having difficulty accessing SketchUp for Schools. In order to assist you I would normally ask you a few questions but you already provided those answers so we can skip ahead to more advanced steps right away.
Can you get me a screenshot of the console tab in developer mode when the error pops up? I may be able to gather some additional information from that to help you faster. I’ll also give something else a try on our end to make sure that you are not running into any firewall issues. If all goes as planned, we should have you back up and running very soon!
Tested again today and it’s working on our side now. It no longer gets stuck at the “Sign in with Microsoft” step. Not sure if something changed on your end, but it looks resolved for the moment.
Also checked our firewall and nothing is being blocked for edu.sketchup.com (and related domains).