Our apologies, but there is no easy way to integrate Shopify. Currently we only support Paypal.
Integrating Shopify can be done through the Code Injection tool but it requires programming skills which may require you to have some programming knowledge. Then again, if you get the needed code from your resource, you can try adding it via the steps in our FAQ Using Custom Code - Code Injection.
You need to be a paying client in order to use that feature.
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