I was not running as a domain admin but the user has required rights.
I was able to run the installation and I have a suspicion on what is causing this:
It has something to do with regional settings since I was able to run the installation package with different language. This is the first time I've encountered this kind of problem since we usually run English installation packages without glitches. For
some reason the updating of installation files causes this. Installation files must include something that is not compatible with the regional settings used in this environment. It might be the "€"-character since it caused trouble when I tried
to install it using a XML-file. For some reason "$" and "£" is OK, but "€" causes trouble. Great...
After installing the server a new problem has a emerged:
The SSRS connector does not install even if the installation files are updated. The SQL Server is 200 R2.
Files are updated successfully but reporting service is not found:
Unable validate SQL Server Reporting Services Report Server Installation.