Everything is set up in Shopify. Follow the steps below once to show the payment button on the Thank you page.
In Shopify go to Settings → Payments. Add a manual payment method named "Pay via Zoho" (or similar). You can leave instructions blank; the Thank you page will show the payment link.
Click the button below to open your store’s Checkout settings in Shopify. Then click Customize to open the checkout editor.
Open Checkout settingsIn the checkout editor, go to Thank you page. Add the block "Zoho Payment – Thank you" from this app. In the block settings, set Payment app URL to:
Copy the URL above (no trailing slash). Paste it into the block’s "Payment app URL" field and save.