Podcast Subscribe Button not working

Hi everyone
for a couple of weeks I am trying to fix my Podcast Subscribe Button. It is not working and it is annoying and frustrating because people keep asking me, why they cannot subscribe.
I currently use the workpress subscribe button but I think there might be a problem with my site being https only. In the podcast apps is shows errors saying something like “too many follow up requests”.
I also tried the Podlove Subscribe Button but it is not even displayed when adding it to my template.

Wordpress version 5.1.1

I’m very thanksful for some help!!

Cheers, Kim