Thanks for reaching out, welcome to forums and I am sorry to hear about the issue you ran into.
To find out more about the issue you're dealing with, have a look at the following article
Essentially, the reason you're receiving this error message, is because you're connecting to the wrong Uplay account, than it was linked to when launched for the very first time.
To have this resolved, you need to make sure you are logged in to the right one and error will no longer appear.
Should you still experience difficulties with this, we are more than happy to look into this for you, however in order to proceed, we will need you to reach out via one of the following channels, as it will involve discussing account related details:
1. Support website
Should you have any questions, let us know!