I own the Ender 3 Pro BUT,
I have the silent motherboard 32-bit and installed with the firmware: "Ender-3 Pro_HW4.2.7_SW2.0.9.03_SpritExt_H300" because it seems like its the only one meant for the extruder pro kit. It complains that the BL-Touch is not attach to it. I can see it in Octoprint error message and gcode terminal.
With the default firmware on it, it did manage to start the print till its heated to 228°C, but Octoprint couldn't proceed after the printer heated. It just waited till infinity.
Additionally the Display is not working at all, its beeping and mid beeping a louder beep is repeating every second. Not sure why, but the display claims to support Ender 3 Pro, Ender 3 and Ender 3 v2.
More Sources:
What firmware would be the correct one for the extruder? Should I return the Display?
Silent Mainboard did work with the stock-extruder. It stopped working with Octoprint after replacing the extruder with the new one, but seems to heat and move correctly.
Marlin is the name of the firmware. It can be configured for any printer. It stands between the cpu of the mainboard and the motion system, telling the cpu what hardware you have and how to use it.