The Scotto9 is a 9-key macropad. The one I built uses NK Milkshake switches and is the macropad featured in my "How to Build a Handwired Keyboard" video. I often recommend this project to people just getting into handwiring because it's simple and teaches you all the concepts for a larger project.
If you’re interested in getting one assembled, contact me and we can discuss the components and other details for a commissioned build. However, the files are available for free here if you want to build one yourself.
When looking at the back of the board, the columns (blue) go to the following pins on the controller from right to left: 4, 5, 6
Then the rows (red) go from top to bottom: 15, 14, 16
Keep in mind, you can connect anywhere on the column or row to the controller, it doesn't need to just be at the end.
You can find the firmware files on the qmk_firmware repository or you can compile them online using the QMK Configurator. However, QMK is often slow at getting changes merged and because of that you can find the most up-to-date firmware on the ScottoKeebs Github repository. Also available are the pre-compiled firmware files that you can simply download (right click, save as) and flash using QMK Toolbox: