From the fact that the media library is empty, it sounds like this has nothing to do with ACF per se but with WordPress itself, like, the clone script has made a copy of the site but not a real clone. Doing an internet search for “wordpress emtpy media library” brings up many suggestions for possible reasons and solutions, wrong directory permissions for the uploads directory being among them. Another suggestion was to change the file upload path in “Settings → Media” and then change it back to default blank. Also, perhaps re-updating WordPress (in “Dashboard → Updates”) might help?
