Hello Vasilisnikolo,
I am Jaspreet Singh an independent advisor.
Windows Ink comes preinstalled on every windows installation but Whiteboard needs to be installed manually from the Microsoft store.
You are however prompted for the install if you use a compatible stylus or if you press widows key + W on a device that does not have it installed. Both windows ink and whiteboard are free and do not need any subscription though you require a Microsoft account.