Promotion Selections
Once the Promotion Benefits are linked to the Promotion Conditions, the final step is to define the Promotion Selections.
Promotion Selections
At the end of Promotion card, it is Promotion Selections card part. Specify which customer you want to assign this sales promotion to. Toggle the All Customers button to apply to all. Select the suitable type otherwise.

tip
Here is a link to the Microsoft help on Customer Price Group setup.