If Using BuddyBoss, do I also need BuddyPress installed

Hi there – If by BuddyBoss you mean the BuddyBoss platform (not the Boss theme from the BuddyBoss company), then no, you should not need BuddyPress as well. In fact, it’s probably impossible to run both BuddyBoss and BuddyPress side by side.

If you’re having problems with digests being sent, first try some of the troubleshooting steps at https://github.com/boonebgorges/buddypress-group-email-subscription/wiki and https://github.com/boonebgorges/buddypress-group-email-subscription/wiki/How-to-troubleshoot-missing-emails