I have used the Pay Now button in the Checkout page as a trigger to post a form. The form contains hidden inputs with the values obtained from the Data Store as in
Remember that the Data Store stores the information as an array, meaning that you will need a multiple insert database action.
Edit: I have just updated the Git repository using Data Store. You can find it here: https://github.com/Wappler/wCart. If you do not want to install the project, open _checkout.html and go to the bottom of the page to see the relevant section.