How many partitions do you have on that Win10 machine?
Maybe post a Gparted screenshot of your partitions here.
How did you try to install Zorin, did you use "Something Else" method?
Have a look at this: Before you install
Which flavour of ZorinOS are you trying to install e.g. Core, Lite etc?
Is Zorin installing, but you are not seeing a grub menu on boot?