Six thousand sits comfortably inside the sync client's honest range, so that is the tool, with the scale breakage list being exactly the right question since demos never mention it.

The setup: in the SharePoint library click Sync, which hands the library to the OneDrive client on each laptop, appearing in Explorer under the organization's name as ordinary folders. The Files On-Demand decision then shapes the field experience: on demand keeps placeholders downloading per open, wrong for connectivity challenged sites, so right click the synced library folder and choose Always keep on this device, forcing the full 6000 local, the offline posture the laptops actually need. The initial full download per laptop happens on office bandwidth before deployment, obviously in retrospect and forgotten regularly.

The scale breakage list: path length first, SharePoint's folder nesting plus long filenames overflowing the classic Windows path limit and syncing errors on exactly the deepest files, mitigated by enabling long path support or flattening the library's worst nesting. Invalid character collisions second, files named with characters SharePoint tolerated in odd ways surfacing as sync errors per file, the client's error list naming each for renaming. Library scale third, the client's comfort declining as libraries head toward six figures of items, your 6000 being safely inside but the library's total item count including other folders being the number that matters, worth checking against the whole library rather than your project's slice. And churn behaviour last: field edits sync back on reconnection with conflict copies generated when two laptops edited the same file offline, the merge discipline being a people process the technology only reports on.

The one time copy alternative for completeness, when laptops need a snapshot rather than a living sync: the library's Download button zips selections, and PnP PowerShell scripts pull a library wholesale for automation, both leaving the laptops disconnected from future changes by design, occasionally exactly the intent.