To use the open-source extension you need to purchase it in our marketplace, once you got the extension you only need to go to your builder, click on your app/website that has enabled the open source extension and clicks in the button to download.
When the download finish you're able to build anything you want on top of the Ordering product. After your purchase, you will get your files according to the Open Source App you purchase in 10 working days with instructions on how to customize.
Glad we can help
Have a nice Ordering
Regards, Pol Zepeda