Adding ESRI REST layer - what am I doing wrong?

I am trying to add an online layer from this government site https://geohub.lio.gov.on.ca/maps/mnrf::provincial-digital-elevation-model-pdem/about.

It provides the URL for the service endpoint as https://ws.geoservices.lrc.gov.on.ca/arcgis5/rest/services/Elevation/Ontario_Provincial_Digital_Elevation_Model/ImageServer

When I try to add it, it doesn't work. I tried both ESRI REST options, though I am pretty sure it would as raster tiles given that it is a digital elevation model.