Setup Cross Domain Tracking

If you are using the Shopify buy button, where the referral link directs to this landing page site and then the customer clicks on the buy button to checkout in Shopify:

For this Install the app on your Shopify account.

i. Then post installation, open Settings > Advanced > Third party tracking section and embed the code from there in your store theme's footer area.

This will ensure that cross-domain tracking is established, i.e. the customer comes on your store's page with an affiliate's link > clicks on the Shopify buy button > completes checkout at the Shopify checkout page > the app can track and record such sales.

ii. After this, open Settings > Advanced Settings tab > Cross Domain Tracking section > Click Setup > then click "I don't have a shared key" > click Submit. That's it.

iii. Finally, in Settings > Advanced Settings tab > Default referral link section. Set the URL of the landing page that you create. So referral links direct customers to this page.

Here is the guide for this: (Guide)