Hi Franz,
I've only used DOSBOX once, a while back to play an old game in Windows 7, so know little about the problem.

For what it is worth, here is one link:
https://answers.microsoft.com/en-us/windows/forum/windows8_1-security-winacc/no-administrator-rights-on-windows-8-or-windows-81/58575911-e009-408b-a6ea-f980d9295888?auth=1

Came across link to W8.1 version of DOSBOX:
https://docs.google.com/document/d/1KEfB40UonLS5XfRw3k9Crii7YEUUxHqBX0xE8cSwh-s/edit

- Brian