it looks like their thing pulls built containers from dockerhub, or uses some plugin to install verified pre-built "community applications". It all seems... sort of wrapped in their world.
I've gone ahead and built the container with a baked in certificate named "webcore" and pushed it to dockerhub. You may be able to install it via their "add container" button using the docker repo:
The run command in regular docker would be:
docker run bmcgair/webcore-docker:latest
It listens on port 443 by default so you'd just https://unraid-ip, click through the warning about the ssl cert, and you're good to go. That is, unless something else is already running on 443, in which case you'd need to run it on a different port. I don't know how to do that on un-raid, but for regular docker it would be:
docker run -p newportnumber:443 bmcgair/webcore-docker:latest