A new member will go to the first touch, as in the first person that they opt into on their email list and the first person they have engagement with.
For example, if Sally clicks on Abby's landing page affiliate link from anywhere, Abby becomes cookied to Sally.
If Sally exits the funnel without purchasing and within 45 days clicks on a landing page affiliate link from Bob and makes a purchase then Abby gets credited with the sale not Bob.
Affiliate links may be cookied for 45 days but direct checkout links override this rule.
For example, if Sally is cookied to Abby and Bob gives Sally her Direct Checkout link then Sally becomes a customer of Bob.