Choose what a discount applies to
For a product discount, choose which things it reduces, in the Applies to section. An "amount off order" discount always applies to the whole checkout, so it has no Applies-to section.
You need the owner or manager role.
Choose the scope
In Applies to, pick one:
All products - every item in the checkout.
Specific product types - choose from Memberships, Bundles (punch cards), Drop-ins, Class bookings, and Appointments. Add at least one.
Specific items - search for and pick individual products, class types, or appointment types. Add at least one.
Troubleshooting
There is no Applies to section. Your discount is an "amount off order" discount, which applies to the whole checkout.
"Pick at least one product type" or "Pick at least one item." Add at least one to the list.
Related
Create a discount
Set who can use a discount