Connor,
According to the VATUSA database, your ARTCC selection went through. However, you will need to contact the staff at ZKC regarding your access to their site, and addition to the roster listed on their site.
Just to note, it also appears that you were previously a member of ZKC using a different VATSIM account. If you had previously done any training with them, passed any of their tests, etc., it's going to be a whole lot easier for everyone if you use the other account, as you are probably already in their system. That all completely aside from the fact that it is against VATSIM regulation to have more than one account.