Problems adding new mep

Hi!

First of all, thank you for a brilliant plugin!

We have a issue; We are planning to replace the current maps with a custom one. We have tried to use both layer and custom basemap with little result, we tried to follow the guide at the FAQ regarding the Austrian map aswell.
The map we are trying to use is a opengis sollutions located here:
https://geodata.npolar.no/arcgis/rest/services/Basisdata/NP_Basiskart_Svalbard_WMTS_25833/MapServer/WMTS/1.0.0/WMTSCapabilities.xml

Is there any chance for some of you bright minds out there to take a look at how to display this map properly in Maps Marker?

Thanks alot in advance!

Best regards

https://www.ads-software.com/plugins/leaflet-maps-marker/