Use +SymLinksIfOwnerMatch option in .htaccess for Drupal on Virtualmin
The default Drupal 8 .htaccess provides +FollowSymLinks.
There is an old discussion about that on the Virtualmin forum.
A patch is under creation for Drupal 8. It changes the Options +FollowSymLinkson the root .htaccess directory.
by
Options +SymLinksIfOwnerMatch
You should also change this on the sites/default/files .htaccess