Hm, I'm not sure there's a way to play games like this on iPhone. In some cases, itch might allow you to play directly in browser, but that can still be a bit tricky. You will likely need to download this on a computer, as it's not a phone app.
Yes, sorry to say but all these games have to be played on a computer: Windows, Mac or Linux. I haven't ported the game to mobile, which is a separate system itself. Sorry! Please try it on one of those ^^