I am a bit confusing with 2 noun words are combined together because I've seen many phrases such as web data, car data, human resource, child care ... etc.
Here, instead of the organizational data, can I write the organization data? And if no, why?
These are two different structures. One is a simple adjective-noun combination, the other is a compound of two nouns. Similar compounds:
Both "organizational data" and "organization data" are fine, but as Khan mentions, organizational data feels more idiomatic.