Welcome to the Community, @Ggg8. Let me give you insights about adding a Pay Now code or link on invoices in QuickBooks Online (QBO).
The Pay Now button allows customers to pay their invoices online. It's available for QBO users with QuickBooks Payments subscriptions. Currently, QuickBooks Payments is available for QBO US. With QBO Singapore, you look for third-party applications that support the online payments feature.
For the time being, you can process your invoices and payments manually. I'm adding these links as your reference:
If you need to track on-time sales, record sales receipts. Here's how: Create and send sales receipts in QuickBooks Online.
Let me know if you have any other questions while handling your invoices. I'll be right here to help. Keep safe!
