Toki is directly connected to Shopify. When all integrations are connected, Toki accounts are created whenever someone does a reward activity such as make a purchase, sign up for a newsletter, engage on social, etc. This means your users do not need to "claim" their points or opt into anything in order to start engaging with the loyalty program. 

As soon as they login to Toki for the first time, they are considered to have "joined".