Single-player use works well.

In my Fabric server, the mod doesn't seem to load on startup (I have other mods that load fine). And when a player dies, nothing happens.

What is the process for use on the server side?

I found a solution and it works! I'll post it if that helps.
You need to configure the mod in single mode, and copy the tombstones configuration file to the server (folder named "config").
This mod is really cool. Great to use it on my server.