Hi.
There is an old topic with similar content from 2020. I really accept that MIT has a lot to do. And of course I appreciate their support in giving us such an amazing coding platform for free. But without HTTPS it is impossible to open Appinventor in Google Chrome. I work as a teacher. We only use Google Chrome on our PCs.
Please switch to HTTPS!
Thank you from Berlin, Germany
Are you talking about using the Google Chrome browser? or a
Chrome PC ?
My Chrome browser works with App Inventor 2 fine using the provide link which seems to be http. Your issue is not Chrome but possibly your school IT department blocking any http link as a guess. Check with your IT department and ask if they can white list ai2.appinventor.mit.edu and the other links indicated at the bottom of the link about School IT/Nework Admins.
App Inventor 2 is a web application. This seems to indicate the link may already be https (and not https .. sorry it is still http ) 
To test the IT blocking theory, you can try using Chrome from a non school network. What happens? If Chrome works ok in your home environment but not the school environment you might see if there is helpful advice in this link> * School IT/Network Admins: Information specific to school networks (also helpful for conferences and hotel situations)
What happens when you try the above link Ingo? Are you trying to use App Inventor with the Companion or the emulator.