To use cloud features, you need to log in with your pixiv account.
You can do so from the bottom left of the app's home page.
Once logged in, your canvases will automatically sync to the cloud.
Canvases that have failed to sync will display a icon.
If you want to sync a canvas that failed to sync, tap the icon to try syncing again.
If your cloud storage is full, your canvas data will not sync.
You can upgrade to a Pastela Plus plan to add more cloud storage capacity.
To learn more about the storage capacity and pricing for each plan, please check here.