https conversion not desired

[riekeltkeuter]

Expected Behaviour

URL for audio is entered as eg: http://data.prekenarchief.nl/diensten/de-zaaier/De_Zaaier_Deel_3.mp3

Actual Behaviour

Website prekenarchief.nl is on https, managed via realysimplessl plugin.
Frontend audio player uses url https://data.prekenarchief.nl/diensten/de-zaaier/De_Zaaier_Deel_3.mp3,
instead of the entered url with http: only

Steps To Reproduce

Platform

Sermon Manager Version: 2.16.3
WordPress Version: 5.6
PHP Version: 7.4

Any Additional Info

Please notice the difference between the entered (right) (download) url (http:) and the url (https:) used in tag: (Source from frontend)