Replace your Setup.dll with the attachment and install again. No need to compress the game again. There is a missing file inside Setup.dll with the version mausschieber shared (oo2core_5_win64.dll). This should fix the issue.
@mausschieber: Please update your DiskSpan_Gui folder (exe + Resources folder) with latest files due to a bug.
https://imgur.com/a/OK3R5XJ