Hi @pmaert! Thanks for reaching out, and apologies for the trouble! It sounds like you're almost there!!
When you imported the QuickStart, did you select "Assign a new MAC Address" for all network adapters? It looks different based on your host operating system, but that step is very important to have the licenses activated properly.
That said, if you are in an offline environment (no access to the internet) or a semi-offline environment (some access to the internet through a proxy), that can cause problems for the license activation process.
Ultimately, if you try to re-import the QuickStart with a fresh MAC address and that doesn't solve your problem, I can walk you through the license activation process! Unfortunately, if it does not work automatically, the fix is a bit manual 
This is mentioned here: https://support.rstudio.com/hc/en-us/articles/360014001734-RStudio-Team-QuickStart-VM-Troubleshooting
And here (in Step 2): RStudio Team QuickStart VM - RStudio