If you are getting 500 error you need to turn on the debug mode (see FAQ below) to see the error message. Follow the steps from this FAQ
Copy the error message and send us support ticket at support.perfexcrm.com
Support from the comments section on Codecanyon is not offered. If you have any problems or question open support ticket at http://support.perfexcrm.com
Sorry to say this but not.
Only customers with purchase key can register in the support system.
Buy Perfex CRM and register with your purchase key, we will be happy to answer to all your questions and assist you with every problem