Hi @manuelr, sorry to hear the issue is persisting for you.
Please kindly get in touch directly with Tobii Tech Support Team who should be able to direct you either by mail or remote session the appropriate steps to remedy the installation problems.
You can raise a ticket here @ https://help.tobii.com/hc/en-us/requests/new
In the meantime, you might try an uninstaller program (such as IObit Uninstaller) that may be able to completely remove all traces of the Tobii Core files.