Custom Camos Don't Work "invalid IWD files"

I have custom camo files that I have put into my “main” folder using the methods in these two videos. When I try to join servers to test if the camos will work, the server doesn’t let me join and says “invalid IWD files referenced”.

Video tutorials I used:

Whenever I start the game it also says the localized_english_iw07 is invalid. Is there another way to put in custom camos and still join, or does it not work with the new 21.1 client version? Or, is there something I may have done wrong?

You didn’t do anything wrong, this method is no longer works.

Ok, thanks for letting me know. Is there a new method for it now?

Unfortunately no, you need a mod for that.

and would you happen to know a method that involves making a mod and allows me to play on servers?

No, as the mod needs to run on the server side as well.