Learn Italian: La sinergia è fondamentale per tutti noi. - Synergy is fundamental for all of us.

In Italian, when the quantifier tutto (or its variations like tutti) is used with a stressed personal pronoun like noi, you do not use a preposition like di for 'of'. You simply place the pronoun directly after the quantifier: tutti noi (literally 'all we').

Can I change the word order and say noi tutti instead of tutti noi?

Yes, noi tutti is also perfectly correct and means the same thing. Putting the pronoun first can add a very slight emphasis on the group itself, but in everyday conversation, tutti noi and noi tutti are used interchangeably.

Does tutti change its ending based on who is in the noi group?

Yes. Tutti acts as an adjective here and agrees with the pronoun noi. If the group represented by noi were entirely female, you would change the ending to make it feminine plural: tutte noi.

Why does the sentence use the definite article la before sinergia when English just says 'Synergy'?

In Italian, abstract nouns used in a general sense almost always require a definite article. While English drops it to say 'Synergy is fundamental', Italian requires la sinergia to show you are talking about the concept as a whole.