In "FIFA's player transfer rules", "player" and "transfer" are both nouns. But they function as adjectives. They modify "rules" jointly If by that you mean that they work together, they should be hyphenated. (form and function). Not all attributive modifiers are adjectives.
:up: 2006 gave us a simplistic account of the use of hyphens, which in the majority of cases but not in all cases is applicable. Perhaps you meant a basic account. It wasn't an exhaustive one, but it covered the main point of whether the adjectives work independently or together.
the most respected member :tick: (most and respected? - no!)
the most-respected member :cross:
That "most" is an adverb, so the above example doesn't apply to the question of compound or independent adjectives.
Another way you can know that you shouldn't use a hyphen is if you can add "and" between the two adjectives.
The above guideline does not apply to all situations. It can be used by people who already have a good understanding of English and are deciding whether to use a hyphen to separate two adjectives.
Central American states :tick:
Central-American states :cross: This would be correct to describe states located in the middle of the USA.
However,
Afro-Cuban music :tick:
Afro Cuban music :cross:
I don't know what to say about the above, maybe because of "Afro".
The following compound adjectives are not normally hyphenated:
Where there is no risk of ambiguity:
"a Sunday morning walk"
They are not hyphenated because both adjectives independently modify "walk".
African-American people :tick:
African American people :tick:
One sees both of the above. But I would hyphenate because their African heritage and American citizenship are tied together. It's not simply a matter of the two separate adjectives.
FIFA's player transfer rules :tick: -- no ambiguity Maybe not in this case, but there could be examples that are ambiguous. More importantly, the two adjectives work together to modify "rules".
"FIFA's player-transfer rules" :tick: