Heyo, could you link the wiki this happened on, and if applicable, the page?

Your account is very new. IIRC, this wiki requires it to be at least 4 days old before you can edit/post, so you'd have to wait for that time to come.

Oh! I didn't know that! How did you know that!

Well, if you see Special:listGroupRights on that wiki, it shows the permissions. And as you can see here, "posts:create" and "threads:create" are only permitted to Autoconfirmed users, which is automatically achieved after your account is 4 days old :)

Oh wow! It is unacceptable they don't even inform the new users about that!

Thank you Garfield :D

Since we get posts about this particular issue a lot here and you've gotten your answer, I'm going to lock this now. 🙂