Troubleshooting
How to find out whether mod_proxy works properly or not?
Once you placed the .htaccess code generated by Post Affilaite Pro to the 'custom location' where the site replication URL (https://support.qualityunit.com/376004-Replicated-Site-URL) points, click the "Check if .htaccess is working for this location" button.
If you get some error message, then try to remove the "P" parameter from [L, P, QSA] in the .htaccess code. Now try to click the "Check if .htaccess is working for this location" ...