Use of OSM Maps

Hello community,
I have a question regarding the embedding of OSM (OpenStreetMaps) into my website.

click here to see what i mean with OSM not loading:

The marker is loaded, but the map itself is not being loaded.

I tried several plugins supposed to do this:

Right now, I’m using “Embed OSM

Does anyone of you have a good suggestion on how to get that plugin to display the map?

Thank you!