Does Engage work on a business unit level or enterprise level?

DESelect Engage works on a business unit (BU) level.

Within each BU, different contact categories / campaign types / rules can be defined.

This also means that saturation levels for a contact that exists in multiple business units are managed per BU, where the rules for each business unit are respected.

In BU 1, the campaigns received in BU 2 are not known. There is currently no aggregation of campaigns across BUs, though this may be added in the future.