If looking at the "Flex Innovations Edge 540 Green_CS" linked above, in the middle of the screen is the text "This color scheme requires". Below it is a link to "Extra 330sc_EA". That is the one to install first.
"EA" (Entire Aircraft) are usually ones made by a user and uploaded. Stock planes, ones purchased from Steam, or included in really old Expansion Packs or Add-In supplements will be listed as such.