
Hello phjo,
Whilst we don't yet officially support macOS 11 ('Big Sur') or Apple-CPU Macs, and I don't know for certain whether it might have been caused by some difference in those platforms:
- The extra space character shown in the error message on the screen almost certainly isn't relevant; it will just have been added on the screen to allow the very long space-less line to wrap, so as to avoid the message box becoming excessively wide. If you look in the log ('View | Activity log') you will see the exact text of the message, without any such added spaces.
- My guess is that there is some file/folder within that particular sample set's installation package (or the preceding one that you installed) that has some unexpected file permissions that are preventing it from being deleted on macOS. Try rebooting, then (before launching Finder), use Finder to manually and completely delete all files/folders within the following folder (but not the folder itself):
/Users/phjo/Hauptwerk/HauptwerkSampleSetsAndComponents/TemporaryFiles
... then empty macOS' 'trash can' for good measure.