Add a device
Open My Devices and create a separate device password.

Open My Devices and create a separate device password.
Install the official Nextcloud client; use the server address shown in your panel.
Select the folders to sync.
It is shown only at creation. Revoke a lost device from your panel.
In a browser upload, you choose and send a file yourself. With Windows sync, the client follows changes between a selected local folder and online storage. You do not have to sync every folder. Start with a small working folder to understand the connection, checking both local disk space and your account quota.
Sync is not an independent backup: a change or deletion on one side may propagate to the other. While offline, changes do not reach the server immediately. After reconnecting, wait for the client to indicate completion. Seeing a file locally does not prove its online copy is up to date.
Use the official client linked from My Devices. Take the server address and device-specific credentials from your panel, not a random login page found online. Giving each computer separate access lets you revoke a lost device without affecting the others. Store the displayed password securely and keep it out of email and support messages.
When a conflict is reported, examine both contents before deleting either copy. The same document may have changed on different devices. See the Windows sync guide for connection interruptions, quota warnings and selective sync. Android, iPhone and macOS apps are currently marked Coming soon; use the web panel on those devices. This page does not claim that background mobile photo uploads are enabled.