Firstly, make sure the mod is fully downloaded. The mod is about 20 GB and you can check that it's properly downloaded by right click Empire at War, select properties and then pick workshop; if it says 0B, it hasn't downloaded properly.

Secondly, grab the steam code mentioned in the workshop description and put it in your launch options, which you can access by right clicking and selecting properties again.

Thirdly, make sure you are launching Forces of Corruption and not Gold Pack.

If you have further issues, then please let me know.

THANK YOU