Advice on sync for new user?

I am a new user to DT. I’m testing out DT3 on my Apple machine, and am hoping someone gives me some advice on strategy. I want my database to be accessible from Apple desktops, and from a few iOS devices. I want my data to live only on those machines (for security), although if it’s encrypted, I suppose using Dropbox or similar would be ok. What is the best method, and what’s the difference, operationally speaking, between the Server option and the Sync options in the Preference panes?

The Server has nothing to do with syncing. It is an internal web server for broadcasting databases on a network.

Syncing is covered in the built-in Help > Documentation > In & Out > Sync.

Also, a quick overview is here: