You can use the mentioned project as a baseline to recreate something very similar. You can even import it into your own accounts to dissect. We also have a whole webinar dedicated to advanced scrolling & dragging, which also includes this example. Here is a link to our webinar: https://support.proto.io/hc/en-us/articles/115000637591-Advanced-Scrolling-Dragging
This project seems to use a very similar setup to another project here: https://spaces.proto.io/project/487398B3-D602-255B-6CCE-95EDED3805D3/Drag-and-Drop-Variables/.
You can use the mentioned project as a baseline to recreate something very similar. You can even import it into your own accounts to dissect. We also have a whole webinar dedicated to advanced scrolling & dragging, which also includes this example. Here is a link to our webinar: https://support.proto.io/hc/en-us/articles/115000637591-Advanced-Scrolling-Dragging
Happy Prototyping! :)