I doubled checked that that looks good. I don't seem to get error message. Maybe i'm crazy but after you just replied i was able to create a database. holy smokes I think I figured it out I see if you go over 4 letters the button fades out.
There is a max database username length limit. For MySQL/MariaDB 5.5/5.6 - up to 16, MySQL 5.7+ - up to 32, MariaDB 10.x - up to 80. Maybe that's the root cause of the issue?