I was having the same problem, so I contact the M Audio support and their response was:
"Please try to access the site using Incognito mode in your web browser, if that does not work, try with a Free VPN client."
I tried the incognito mode and it doesn't work, but using a free VPN extension at my chrome browser I was able to create and sign in to my account.
There is obviously something wrong with the programming of this website for whatever reason. I had the same problem awhile back and was able to force it to suggest a password that I should use instead of my own. When I chose their (M-Audio's) password, it worked and allowed me to create the account. I don't know for sure if this is exactly what might be happening to you but it does not hurt to try. Try to get the form to suggest a password to use instead of your own. Does not hurt to try. Good luck!