Emulator startet weder in Firefox noch in Chrome (Emulator does not start in Firefox or Chrome)

I don't know, but somehow you have to beg for all this AppInventor stuff. Nothing works without praying 150 times. It's annoying, what rubbish, it makes you lose interest in learning. The emulator basically doesn't work. When I read the help page, I feel like I have to test 100 things. What are the developers actually there for?

What exactly is your issue?

Use the companion app over wifi instead ? I assume you have an android phone/device ?