1. Log in to your Plesk account.
2. Go to Websites & Domains > Backup Manager.
3. Click on Remote Storage Settings.
4. On the right side of Password Protection, if it displays Disabled, click on change.
5. Tick Use password protection and enter a password. Then confirm with Apply.
Ensure that you store your password in a safe place. You will need it when restoring a backup. In case you have forgotten your password or do not enter one, Plesk will restore your backup with a random database password.