Please follow these steps :
1. Install and activate the wplmsblankchildtheme if you are not using any child theme .
2. Now in wplmsblankchildtheme folder please create a “paid-memberships-pro” folder .Then inside the “paid-memberships-pro” folder create pages folder
3. upload the given levels.php file in the attached levels.zip file in your wp-content/wplmsblankchildtheme/paid-memberships-pro/pages folder .