Focus Cube Version 2 for SCT

[Whirlpool51]

Do you have to pre-focus your SCT telescope first?
So the software knows where the initial focus position is?

I have another focus cube fitted to a C9.25, so I can image and focus on Jupiter. But I am having trouble finding the correct focus position with a 2.5x Barlow and ZWO ASI174MM.

Can anyone here please tell me what I need to do.

I control everything via a PPBA and ASCOM.

Thank you