This is the Forge version of the mod, if you're looking for Fabric click here.
Cooperative Advancements is a simple mod that automatically grants advancements to all players on a server whenever someone earns one. It also automatically synchronizes every player's advancements whenever someone logs in.
This mod requires Iceberg, you can download it here.
Client / Server
For dedicated multiplayer, this mod only needs to be installed on the server. For LAN multiplayer, just the host needs to install this mod on the client.
You are free to use this mod in modpacks.