pixel_player606854558
Please check out the two posts above yours.
Concerning the nickname, I guess that is for the teams feature? You will have to try on. Many names are taken by now, you can try and add numbers to the nickname, if the original one is taken.
Letters and numbers are allowed. No blank space, no special letters like -#+:@&€ etc.
You can also double, tripple etc certain letters to modify your nick name.
Like niiiiicknaaaaaaame 😉😄
If you want to change your user name here in the forum, we have help with that here:
https://forum.pixelfederation.com/diggysadventure/d/189657-how-to-get-a-username-instead-of-a-number