A) through linking the devices with one identity for automated folders' sharing;
B) manually sharing each folder individually via a key/link/QR code
The main reason to link the devices is to automate the sharing of the folders across them: each and every folder that you add to Sync on one device will automatically be available on all the other devices in the "My devices" list with full RW access to the files.
It works for devices that are not linked with one identity. With this approach you have control over what device gets what folder with what access privileges.
STEP 1. On computer 1 click the "+" button and choose the type of folder to add, browse through the system and choose the folder that you want to share.
STEP 2. From the opened menu or by right clicking on the folder in Sync UI -> Share, choose the parameters and means of sharing.
- Choose the access mechanism key, link or QR code. They are all secure, but have different flow and functionality. Read about keys and links. QR codes can be used by mobile devices.
- Choose the access permissions for a remote device.
Read-Only permissions mean that the device will be only able to download files, but not propagate local file changes
Read-write permissions mean that file changes made on the remote device will be synced to other connected peers.
Owner (available only for Advanced folders) gives Read-Write access to the share and additionally allows the device owner to manage the access permissions for others. See here for more details.
- Choose the sharing means: you can send the key or link via e-mail (default mail client will be opened, if installed) or simply copy the key or link to clipboard and send it to remote devices using any convenient and trusted way (e.g. a messenger)
STEP 3. On a remote device add the shared folder to Sync
On a mobile device click "+" -> Scan the QR code.
On a desktop device in Sync click "+" button -> Enter key or link, and paste the shared one here, proceed.
In the opened dialog choose the folder location (it can be a new folder or an existing one with files), and enable Selective Sync if necessary.
Alternatively, one can simply click on a shared link (not key) and it will open in a default browser, providing the option to download Sync if it's not yet installed.
STEP 4. Complete the sharing.
Once a remote device adds the shared folder, an approval request will be sent to the Computer 1. Once Computer1 approves connection or if request for approval was disabled in sharing options, the folder will be added and synchronization will start.
Note, if the remote device stays in "Pending approval" state, but the Computer 1 does not receive any request for approval, this indicates the network connectivity problem between these devices. See this guide to troubleshoot.
To make extra sure you are about to share your data with the right person, you can click on the identity (name) of the person who sent an approval request. This will show the details. Here you can review the person's name, their IP address, fingerprint and approval request receipt date.