My error 
I interpreted the ‘Hour’ setting for the daily scan as being the exact hour…
Looking at the cron file made me realise that I was wrong…
When I wait long enough (I helped it a bit by not complying to the first line in the file) for the time that it is started, it does run.
However, the result is (from clamscan.log):
Thu Feb 18 16:50:01 2021
Scanned Folder: /ERROR: Can't open file or directory
Is there a way to run it more verbose so it will tell what folder cannot be opened?