Can you explain to me when it is more appropriate to use it or one in the following sentence?
One/it should warn about the conflicts.
I don't think there's a big deal using one or another because the meaning will be exactly the same.
This question is too basic; it can be definitively and permanently answered by a single link to a standard internet reference source designed specifically to find that type of information. See the FAQ for guidance on how to improve it.
The meaning is not exactly the same. One used as a pronoun indicates an unspecified single person, whereas it indicates a specific object or collective.
It's hard to tell exactly what the context is here with such a short quote, but
means that someone should warn others about the conflicts.
means that a device or software program, or perhaps office or organization, which was previously being discussed, should warn about the conflicts.
"One" should be used exclusively to refer to people (or people-like things - pets, etc). "It" should never be used to refer to people.
Caveat: "One" can refer to non-people-like things in cases like, "One should warn about conflicts and the other should do something else".