Community Tip - You can change your system assigned username to something more personal in your community settings.
Is not possible to work with Model Target Generator, but I don't know why.
Are you able to login https://developer.vuforia.com/ with the same account/password?
It may be different from those to publish experiences in Vuforia Studio or anywhere else.
Many Thanks, I don't know why, but today works very well, without problem.