Here’s the link to the docker I used. There are a few others on github, but this one seemed like it was the most actively updated.

github.com/sirjmann92/nicotineplus-proper

I liked slskd perfectly fine once I got it going, but I couldn’t get my partner to use it as she was used to nicotine and didn’t like the new interface. Once the Docker was set up in Portainer there was very little additional configuration and the rest was inside the nicotine webui app.