If you are getting 404 not found after you install XFINITY CRM this means that you need to adjust the main .htaccess for XFINITY CRM.
First make sure that the .htaccess file exists in the main folder where you installed XFINITY CRM. If you are using any OS make sure you have enabled hidden files on your MAC.
Make sure that you have mod_rewrite enabled in your server.
NOTE: Only apply the following suggestions if you are getting 404 error not found, the default XFINITY CRM .htaccess file should work good on most servers.