Before answering any questions, I want to say that whatever I was experiencing must have been site-related to Disney+ as I'm not experiencing that problem anymore (at least for now).
I've no access to the log - but i can't see any problem for me with fresh log-in:
You're connected to sign-up country?
You can sign-in with your browser?
Germania
Yes I'm always connected with my sign-up country. I tried using a VPN to acquire things from another channel outside my country and the attempt was unsuccessful, so I've given up trying to do that.
I was going to try logging in with my browser this morning but then saw that whatever issue I was having was no longer there, but I'll make sure to try that going forward.
Do you also subscribe to Hulu? If so, are they separate or did you sign up for a "Duo" plan? Try using your Hulu password for Disney+ when asked for a password. I can't guarantee that it will work. This merger smelled of trouble as soon as they announced it.
Cats4U
I do subscribe to Hulu and the Beta icon is on the screen (has been for a few days), but I had acquired titles shortly after the beta went into effect and there were no problems.
I was basing my reply to the OP on this Hulu help article - https://help.hulu.com/s/article/disney-hulu-activation because he mentioned that he was sent a code to his email address. To me it sounded a lot like what was in the article. I don't know if he noticed it or not but according to his log after he entered the code he was transported to the Hulu site and then after a short time he is sent back to Disney+ and then the log ends. Using only the log it is a guessing game as to what is actually going on. I'm not personally subscribed to Disney+ at this time and so I can't do any testing myself. I am subscribed to Hulu but that won't help to figure out his problem.
Cats4U
I get that "we've sent you a code to your email address" thing when I clear the SF temp directory -- I get it for both D+ and Hulu. As long as I don't clear that directory I don't get that message when trying to log in.
But again, whatever was happening last night must have just been a fluke because I'm able to get in now. Thank you to everyone for your suggestions!