Jetpack can be installed on multisite WordPress either at the network level or for each individual site in the network.
Jetpack Backup and Jetpack Scan do not support multisite WordPress.
Managing Multisite Jetpack Connections
Network Level Connection
With a network-level connection, administrators control which sites have Jetpack enabled and which modules are enabled by default.
Through the plugin management screen, you can enable Jetpack for all sites in your network by going to “My Sites > Network Admin > Jetpack” (Ex: https://jetpack.blog/wp-admin/network/plugins.php):
You can then manage the connection to each individual site:
Individual Site Connection
Each Jetpack site can have an individual site connection. When managing this way, Jetpack will need to be enabled on each individual site.
Multisite Differences
For the most part, features on Jetpack multisite work the same as they do on regular Jetpack. There are a few differences though:
Plans
Each Jetpack site on a multisite network requires its own plan. Plans containing Jetpack Backup and Jetpack Scan are not available on multisite installations.
Jetpack Backup
Jetpack Backup does not support multisite.
Jetpack Scan
Jetpack Scan does not support multisite.
Protect
Requires a network-level connection to Jetpack due to the way logins are managed.
Copy Post
It is not possible to use Copy Post to duplicate posts between sites in the network.
Themes
Adding premium Jetpack themes doesn’t work on multisite via the one-click option.