You install it just like you did on your iMac if you have a subscription. Subscriptions are not platform specific licence like Perpetual Photoshop licences are and the platform installs are different. While with a subscription you can and are allowed to install on both Mac and Windows it a single use licence using Photoshop on both machines simultaneously would violate your agreement with Adobe. I believe Adobe would not take you to court if you do. Using both would make testing add-ons you create for use on either platforms possible. If I were developing add on for both platforms I would use both simultaneously if I had a Mac. I do not and I have had to add some code to my add on when I visited my son who uses a Mac. While JavaScript works on both platform there are different convention between platforms.