Not able to add new ReSharper Ultimate license

We recently received new licenses for ReSharper Ultimate at my company. For whatever reasons the existing licenses which expired a little less recently were not prolonged, instead new licenses were bought.

Now I received an invitation link to acquire one of these new licenses. Unfortunately this does not work for my (while it seems to do for all my colleagues).

When I click the link I receive the following error:

Clicking the link simply yields

however we do not seem to have such an administrator in the organization.

So, er, help? What can I do to finally get my license back?