Hey, if I’m understanding your question correctly, I don’t think you need an Apple product per se. You only need that if you plan on running Zwift using a tablet or smartphone, because they only make the app for Apple products.
If you’re running Zwift using a laptop, you can use any laptop/computer, Apple or non-apple, as long as your computer is fast enough and graphics card is good enough. The minimum specs right now seem pretty minimal. If you have a laptop 2012 and newer, you should be good. Ideally, you want to have higher than the minimum specs so you can have better graphics, but the program will still work regardless.
If you don’t have a smart trainer, you do need to buy an ANT+ dongle ($30 Garmin brand, or $17 generic-brand) to connect your Garmin cadence/speed sensor to the Zwift program on your computer.