you can't use it on iphone actually, either android or your pc! i also have an iphone, so i use bluestacks, an android emulator. you can use a different one if you want, but i chose bluestacks because i've used it before and i know its reliable. so:
you download the android emulator onto your computer. open the set up and get it all downloaded n stuff. then you download the apk to your computer as well. scroll down the first post, there should be a spot at the bottom that says download link, but it says the content is hidden. you have to turn off adblock + make an account (a pain in the ass, but its better than griding coins and keys in heart hunter). the apk took a while to download for me, but i'm not sure if its just my internet or something.
once you have the apk downloaded, you just open bluestacks, look at the top where it says "installed apps", there should be three dots next to the text. when you click on it there should be two options "install apk" or "delete apps". choose install apk, open the folder where you downloaded the apk and select it. the arcana should appear on your bluestacks homescreen and you should be able to play.
i hope this is helpful, this is also my first time using an apk so i'm no expert
I would look into Love 365 from Voltage Inc. (This is only on mobile to my knowledge.) They used to have standalone apps for all of their different stories, but now they're all combined into one app with many available genres. There are occasional text errors because most of it is originally in Japanese, but they're not often enough that it takes away from the experience for me. I really enjoy "Kissed by the Baddest Bidder", which is probably their most popular one. They also have options for free coins through watching ads and occasionally they have specials to read some titles for free.