On Members (/subscriptionmembers), open Add member — this is a short wizard:
1. User Details — First Name, Last Name, and (only if the business requires it) Email. There's no field to set a password yourself; one is generated automatically for the member.
2. Allergens, Dislikes & Diet Preferences — shown only if the business has those profile sections turned on; optional.
3. Subscription Settings — the permission toggles for this member (see next question).

Finishing the wizard creates the member's account. If you gave an email address, a welcome email is sent to it; if you didn't (and the business doesn't require one), the member gets a placeholder address instead and can't sign in independently.