what kind of pop up? set it to windows 8 compatibility and try running it as administrator
from the image I can tell you things are extremely weird...
it seems it is reading DeI since you have the army supply effect
it seems it is reading the pick faction pack since the png with the white penthagon is there...
but it's not giving any testudo scripted effect...
and that combination is super weird... I honestly don't have an explanation
try these steps:
1. Clean out your data folder found in the Rome 2 install folder for Steam. Various mods can be active even without activating them in mod manager.
2. delete the Rome2.exe file found in the Rome 2 directory and reverify your game cache in Steam to check local file integrity.
3a. try again with steam manager
3b. or try mitch's by setting it to windows 8 compatibility and running it as administrator
there is anothre manager that should work with rome2 (never tried myself but many guys say it works like a charm):
https://github.com/Kaedrin/warhammer-mod-manager