System Admin/Site Menu > Plugins > Repositories > Manage Repos
Click the 'Settings' link in the row for File System.
Under the Repositories instances of the site section, click the button to Create a repo.
The next screen will show something like this:
Give your repo a name, select the directory you created in the repository directory. Click Save.
Not done yet ...
In a course Settings menu, Create a File System instance and choose the one created.
In a new blank course ... before enrolling teacher, click the 'Restore' button. Navigate to the repo created for 19 course backups. Select the large zip. Restore to this course ... replaces the blank course you began.
You don't upload the zips via Moodle. You've aleady done that via scp or Samba or FTP.
'spirit of sharing', Ken