Firebase set up for app reporting

We need help setting up Google analytics eCommerce tracking in our app. We are an affiliate site that send leads to our partners so we track add to carts as a page view and the exit link or email send as a purchase with proxy purchase value. We have tried to set up the code but the numbers are not accurate. We are currently reporting in both Google Analytics and Data studio and this project would include setting up a simple data studio ecommerce dashboard.