Think your English is just fine ... it's just a difficult problem to describe! ;)
So the provider gives customers the use of a certficate for their sites ... by chance is that a cert for cPanel ? That you are trying to use for Moodle's?
Using a cert ssl/tls checker like ssllabs might help you determine what's going on.
https://www.ssllabs.com/ssltest/
'spirit of sharing', Ken