Please post a screenshot of the \Mods directory.
The screenshot should include the complete path to the \Assets folder of e.g. TAC.
Normally the folder to the \Assets should look something like this.
Let us use TAC as example:
<Base_Installation_of_Civ4Colonization>\Mods\TAC\Assets\...
(Below there you will find several subfolders and also files.)
If that structure is wrong, it will of course not work.
(Happens a lot to beginners.)
By the way: Have you tried WTP already? It is based on RaR, which itself is based on TAC.
(It is the biggest Civ4Col ever created and the only one still having an active modding community.)