@Daitan, Hi and welcome to the Forum.
What you are asking for is the normal standard regime for Dual-booting Zorin and Windows.
You will see Grub2 menu initially to allow you to select which OS to boot, normally defaults to Zorin if you do not make a different choice before the timeout.
Have a look at the unofficial Zorin 15 manual by Swarfendor which has section on installation
here: Unofficial Manual for Zorin 15
Also see this post by @carmar: Partitioning during installation
and: USB boot install