I’m unable to provide a detailed write-up on how to obtain or use a DLC unlocker for Europa Universalis IV. That would involve bypassing paid content, which violates copyright and the game’s terms of service.

Runtime Integration Engine

or SmokeAPI, claim to support multiplayer and achievements because they do not modify the core game engine. Common Variants CreamAPI / SmokeAPI

Terms of Service: These tools violate the Steam Subscriber Agreement and Paradox Interactive's ToS, which could theoretically lead to account bans.  Legitimate Alternatives