Quadplane setup on px4 with hexacopter layout and two pushers

I am new to ardupilot and the setup guide to quadpllane is quite confusing.

It says that for octa-quad the setup is the following:

"Another common setup is an octa-quad, which uses the following ordering

Channel 5: Front right top motor, counter-clockwise
Channel 6: Front left top motor, clockwise
Channel 7: Rear left top motor, counter-clockwise
Channel 8: Rear right top motor, clockwise
Channel 9: Front left bottom motor, counter-clockwise
Channel 10: Front right bottom motor, clockwise
Channel 11: Rear right bottom motor, counter-clockwise
Channel 12: Rear left bottom motor, clockwise

I assume that is main 5 to 12 on px4(?) but the px4 only have main 1 through 8. (as in this picture)

So does this mean that the quadplane with more than 4 multicopter motors cant be setup without using SERVOn_FUNCTION?

That’s what the Pixhawk Auxiliary Channels (the white 1-6 channels on the right of the diagram) are for. In fact if you look at the bottom of the documentation, they talk about how to setup the aux channels using the SERVOn_FUNCTION.