How to replace the cloud?

Question

Windows

1. 10 people work.
2. Constantly on the road.
We created one cloud with a common login and password so that everyone has up-to-date data.
But when synchronizing, incidents sometimes happen, you delete it, but it syncs from someone, it often happens.
We use mega.nz
Maybe there is a more competent and reasonable way to do this. There is one big nuance, it happens that there is no Internet at the facility.
Thanks, sorry for the confusion.

Answer 1

My option is my own cloud and several accounts. For example, from the good - Nextcloud. But here the question is whether there is knowledge for deploying "one's own".
Or any ready-made comm product - several accounts and a shared folder added to all accounts