Uploaded files as well as backups (automated [if not opting to save backups to an alternate location] or manual) are kept in moodledata/filedir/ but not in any human re-cognizable format/filename.
The Moodle interface, even as an admin level user, gives no tool to 'browse files'. The following query will show all backups:
select * from `mdl_files` where `component` like "%backup%"
The filearea column of the output of the above query will show if the backup file found is in the 'course' area or in 'automated'.
If you have automated backups going to the course area plus an alternative directory (example: /home/m2backups/), that directory must be created manually and owned/readable/writable by the apache user. Moodle will not create it for you. If your automated backups are working, one will see a listing of all backups it has processed in that directory.
Hope this helps!
'spirit of sharing', Ken