If you are having trouble getting muse to let you use it and have received a beta invite email then you can follow these steps to get it to work:
1.) Make sure you are signed in to the muse ai(look at top right for your pfp). If it is not there, click on it and sign in.
2.) Send a message to the ai, any message will work.
3.) After you get the sign up for beta message, tell the ai you have already joined the beta. This prompts muse to check your credentials and verify you are actually in it.
4.) Enjoy!
I hope this helps some of you. It is what I do whenever the message pops up so I hope it helps some of you as well.
This works on and off. But is not regularly reproducible for me. Thanks for the hack though.
You are welcome. I wish it worked 100% of the time for everyone, however I’m not exactly sure why it works nor why it works for some people and not others. Might be a rate limit thing which I know the servers struggle with?
Considering it’s a close beta, I doubt it’s a rate limit issue. Or maybe just some production webapp issues. No worries. But the interesting thing is, it’s the first time I had an experience of the uniqueness of AI. Imagine solving a licensing issue in software by asking the AI to check again.
Like they say, it’s a feature, not a bug! 
Hi! We are looking into this incident, please follow progress and share your experience here. Thank you!
They’ve already mentioned that some rate issues have popped up. It’s mainly why you get the internal server error.