That color scheme goes for military magazines, a tan follower is the new kid in town. Green should still be ok. Black, take it back (to the armorer).
However, many of us prefer the Magpul Gen 3 followers in GI mags. I understand with the tan follower the military copied this COTS follower to avoid royalties.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek