I checked the mail logs and all of the emails are delivered to your address correctly, except the initial activation one. I don't have any details on why, except it's retried about 40 times so far with no success. SMTP as a protocol has not changed fundamentally in around 50 years, and it sucks.
Nevertheless, even without the activation link, password resets will still work (I just tested one on an unactivated account).
If you are typing the password manually, suggest you try copy and pasting. If you are copy and pasting, I suggest you try typing it - there have been cases where copy and paste on systems does not work correctly (leading/trailing spaces, other character transformations).
I don't store unencrypted passwords, or log incorrect attempts for obvious reasons, so I cannot ascertain any further information on why the password you are entering is not working.
The inability to set an arbitrary password was a conscious decision to close the door on the leading cause of account compromises - weak or re-used passwords. That decision is not necessarily final, but that is the state as of today.