So i've been playing a lot of C&C recently and i used to have an issue where i could not play on custom maps. I gave up in the end and for some reason i'm only just trying to get them again. From what I saw nothing worked. I play using Origin and the Ultimate Collection, I mainly play Kanes Wrath and Red Alert 3. I have tried everything that everyone recommended, from finding all hidden files to changing the registry, using launchers, none of them worked.

TO CLARIFY:
There is no folder called "Maps" unless I create one
Even when I've done that and inserted the folder into %AppData% or the actual directory, I launch the game and no maps appear.

You guys seem to be really good at helping people and I need your help badly.

I'm in the same exact spot! Did you have any luck yet? I know it's old as F, but someone got it working ... I would think that custom maps would be the number one thing people would like to have!!

Does the Origin/Ultimate Collection just no allow custom maps? Do you have to modify the .BIG file? Somebody ... somewhere figured it out I'm sure!

Custom maps worked for me in some games (RA2, Generals, ZH, et al.), but I never got them working in RA3 (using origin, I did using steam).

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I believe he resolved his problem.
http://www.cnclabs.com/forums/cnc_postsm148738_Maps-installation--not-found-my-answers-yet.aspx#post148738 

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