Thanks for your answer.
We are completely on the same page, and it is the reason I opened this thread.
Requirements are pretty basic.
We are a team of less than 10 people.
There is one package which contains all the diagrams.
We need the capability to work on that package concurrently and have the package updated in real time.
There is no need to have local copies, we can save the master in a shared drive since I see that it could be locked. I also read that with a different strategy you can concurrently modify and see each other's update simply refreshing a view button.
Whether there would be need to have local copies, I already read there could be several solutions.
I could ask for a professional, that is possible.
Nevertheless, I have a mind and I would like to understand what happens under the wood myself.
I usually do this in similar context, and I think it is the only way to get confident with the software you are using daily.
Thanks again

I will update with the progresses.