I created a few .tpk's that are 4-10GB in size. The were created using Desktop 10.1 File->Share As->Tile Package.
At the time of generation I did not choose to upload them to my AGOL Organizational account. They were created and stored on disc of the local machine.
So now that I am satisfied with them I want to upload them. It looks like I have 2 options.
I'm not sure why it's not working for you. Your account has enough credits and storage space. I suggest you contact Esri technical support so we can troubleshoot this problem.