So the full from scratch installation process for the latest version of MNAI is
Get FFH2 0.41 full install to patch n from here
https://forums.civfanatics.com/threads/ffh2-bug-thread.308020/
Get FFH2 patch o from the same page right below the full install link (feel free to ignore the media pack, it's not needed for what you are doing)
This step can be ignored since MNAI has this bug fixed in it already but for the uninformed/completeness there is FFH2 unofficial patch p located here
https://forums.civfanatics.com/thre...-sons-of-asena-fix-unofficial-patch-p.419634/
Get MNAI 2.71 (latest version as of this writing) from here
https://forums.civfanatics.com/threads/mnai-2-71-release.620889/
Alternatively you can download a rar file that I made with EVERYTHING including the base FFH2 stuff for MNAI 2.71 from here. (file size is 389 MB)
https://drive.google.com/open?id=1h4MwLj7BQhlp06IRUWsMMFTuR_w_1fjD
Now for the complicated part. How you install all of this depends very heavily on where you got your copy of Civ 4 from. If you got it from steam then it must ALL be installed to the steam Civ 4 BTS mods folder located by default (assuming you have a 64 bit OS, most ...everyone?... people do nowadays) is C:\Program Files (x86)\Steam\steamapps\common\Sid Meier's Civilization IV Beyond the Sword\Beyond the Sword\Mods if however you got it from any other source/seller then you will need to find where it is installed at (default is somewhere in C:\Program Files (x86)) and navigate to the correct mods folder of Beyond the Sword\Mods if you have done that and it still doesn't work then you can try finding the mods folder in your my documents and putting it there (I think there was some version of windows, vista maybe, that screwed with the program files folder making people do this). If you have done all of that and it still doesn't work come back and we shall try to problem solve it some more.