An important concept to keep in mind when creating affiliates in Zapier or through the REST API is that affiliates can participate in multiple programs.
If you do not indicate a program to add the affiliate to, they will be archived.
Zapier
To create new affiliates using Zapier, the following actions must take place:
Action in "x" platform/app
Find/Create Affiliate (make sure to check the box!)
Add Affiliate to program
After adding them to a program, you can also (optionally) add them to an affiliate group.
REST API
When creating affiliates using the REST API, it must be done in two steps:
Note: To launch trigger email notifications when the affiliate is added to a program, add ?send_welcome_email=true to the endpoint URL of the second step.