Please make sure your account is entitlement as Primary or Secondary Admin or that is has a seat assigned to it.
More info can be found in this article.
Then, please go to the link below, choose the area you need help with, fill up all the necessary information that describes your issue, and finally hit the EMAIL option. This procedure logs a case under Autodesk and you will be notified for any update about it.
https://knowledge.autodesk.com/contact-support
