Check the /var/log/httpd/ log files to see what Apache is unhappy about. Make sure the repos (created using “svnadmin create” are completely owned by the account that your Apache is running as).
could not begin a transaction [500, #13]
[:error] [pid 1183] [client 172.1] Can't open file '/var/www/svn/repo/db/txn-current-lock': Permission denied [500, #13]
All files and directories in the repo must belong to the account that Apache runs as. That varies between distros so I can’t be definite but possibly httpd or apache. That error is a permissions issue, likely due to file/directory ownership.