After downloading and running the installation for service pack 1 I get this miserable window (see attachment)
I am currently using a 'borrowed' network license as I work abroad.
How can I proceed this installating? Will I need to insert the original USB installation stick?
Yes, frequently to install service packs or updates you need to have the installation media that you used to install them. It's another one of the reasons why I use downloads exclusively.
I believe the updates/service packs check the C:\Autodesk\ folder for the extracted installation folders, so you may be able to copy them from another computer or something as a workaround.