To see how to setup, see chapter called “SYNC” in the “DEVONthink ToGo Manual”, page 35 of the 3.7.1 version.
But, from the problem you posted on your original post, this doesn’t fix your need to have quick and reliable download as you probably won’t have Bonjour available to bring in un-loaded files in front of your colleague. It will help getting everything onto the iOS device while both devices on the local network.
This also discussed in the “DEVONthink ToGo Manual” in the section called “EVERYTHING OR JUST THE METATADA” on page 38.
If you don’t put everything on the iOS device, then when out and about and not everything previously synced, getting an un-synched document depends the sync service to get more on demand.
Dropbox is certainly more reliable than Apple’s services, but it still might be too slow for you in front of colleagues. Perhaps try Dropbox with a database or two that can fit inside Dropbox “free” account if money an issue. Or, set your iOS device to sync everything with Apple’s Services and hope for the best.
Me … I’d get a MacBook Air and load it and keep up to date with everything and use it with colleagues. I don’t have one of those yet, but I do sync routinely with Bonjour, Dropbox, and WebDAV amongst four devices.
DEVONthink Manuals at: DEVONtechnologies | Handbooks and Extras
Numerous postings here how on to setup us Bonjour, findable by search. One that keeps popping up is Bonjour Simplified
Therefore, no need to repeat all that here.