Do You Use Buddypress and Multisite Together?

Yes. Buddypress is very much compatible with any type of WordPress enabled Multisite.

But before starting, you would have to configure the following:

1. wp-admin > Network Admin > Settings > Components
2. wp-admin > Network Admin > Settings > Pages
3. wp-admin > Network Admin > Settings > Options

For Configuring these options, you can get help from BuddyPress Official website, here.