Symptoms
After purchasing the license for CloudLinux extension via Plesk > Extensions Catalog the Install the license to Plesk button appears for CloudLinux extension. In an attempt to press the Install the license to Plesk button the error below is shown:
Failed to retrieve keys for the extension "CloudLinux"
Cause
Via the Plesk > Extension Catalog it is only possible to buy a license for CloudLinux, the button Install the license to Plesk should not be presented there.
The behavior is considered as a Plesk feature request with the ID #PPPM-11786, which is planned to be addressed in the next Plesk release updates.
Resolution
Apply the steps from the official CloudLinux documentation to install the purchased CloudLinux license.