I didn't see that before.
Looks like Planet CNC has a LOT of tutorials and support structure.
They even have a forum.https://planet-cnc.com/blog/?category=tutorials
If you want really good answers to your questions about Planet CNC I would suggest you dig into the support at the Planet CNC website.
I dug a little bit, but I don't really have enough motivation to use my lunch break to find the answers, and I don't have Planet CNC to try anything.
There is a tutorial on how to set steps per unit - I think you need to go through that and refine the steps per unit.
Anything to do with Vectric - THIS is the best place you can be.
Anything about Planet CNC - their place should be the best place.
I'm not trying to blow you off, but the truth is, the maker is the most knowledgeable about the product.