When creating a new folder or adding folders to a group there is an option to pick access level for agents belonging to this group, provided that there are no access level conflicts.
READ & WRITE
Agents who belong to this group will get Read-Write access to the share. It means that all clients will exchange all available data between each other. All new, updated or deleted files will get synced to other connected and online agents.
Agents who belong to this group will get Read-Only access to the share. It means that these agents will be able to download files from others (from those who have RW access), but won't be able to upload anything.
If a file gets updated on a Read-Only agent, this file is invalidated and ceases to sync. You may notice it reported in folder or client details with an icon.
To fix that, enable option "Overwrite any changed files" in Profile assigned to these clients. This option will force RO agents to re-download the changed files from other agents:
1) renamed file in an RO folder will remain there. Besides, the same file with an older name will be re-downloaded
2) deleted file will be restored
3) edited file (changed content) will revert to the most recent version supplied by a RW agent
4) added file will not be deleted, nor will it be synced.
This permission level works almost the same way as Read-Write and Read-Only explained above. The difference is that files in this folder will not get automatically synced to the agent, but will rather be presented as placeholders, making it possible to sync a file on demand. It helps to save free space on a computer and offers a more flexible file management. Details on how Selective Sync folders work are described here.