Step 1
Identify the motherboard.
The linked marlin is either BOARD_RAMPS_14_RE_ARM_EFB or BOARD_ARCHIMAJOR
The RAMPS_14_RE_ARM_EFB only has 5 stepper drivers, the config has #define EXTRUDERS 2 so there are no free extruders to use as Y2
The BOARD_ARCHIMAJOR seems to have 5 extruders.
This is a real oddball controller, people have been working on adding support for it since 2017...
[github.com]
Identify the motherboard.
The linked marlin is either BOARD_RAMPS_14_RE_ARM_EFB or BOARD_ARCHIMAJOR
The RAMPS_14_RE_ARM_EFB only has 5 stepper drivers, the config has #define EXTRUDERS 2 so there are no free extruders to use as Y2
The BOARD_ARCHIMAJOR seems to have 5 extruders.
This is a real oddball controller, people have been working on adding support for it since 2017...
[github.com]