I've only noticed "what could be the possible problem with the file hosters" - I don't blame anyone
, I think I've ran into that sort of things a couple of times that instead of archive I tried to get it gave me an EXE file which was immediately blocked by anti-virus and one of the users online complained about my own zip file which was just a bunch of jsons, not even an app. I do believe this was AnonFiles, but I may be wrong.
Yes. Overall, compilation for Mac OS/iOS is crazy.
First you must own a MAC, at least rent a remote virtual machine
XCode doesn't work on other platforms. Welcome to wonderful world of Apple. However, there is a way to workaround this issue, an illegal one (Hackintosh, I didn't try it myself but I don't see a single reason why it shouldn't work), but up to you to decide.
Second, you need a (release) certificate to sign your builds. Unfortunately I cannot help here, I've just been using ones I have at work, I don't know how to create ones myself. But it should be possible in Apple Developer website. I've made some developer (not-release) certificate there, it's actually almost trivial once you get the idea how the platform works.
For Mac OS and iOS Unity exports an XCode project. So the next step (even if you are using Unity under MAC) is to open the exported folder in XCode and press compile. You'll run into bugs and issues there - some Unity versions conflict with some XCode versions, so you're most likely to have some problems. But all of them have solutions that are easily duck-duck-googlable, you're not alone
This is all you need to make Mac OS builds. I've seen some adult games (Moxie Touch?) even releasing "unsigned" or "not properly signed" Mac OS builds that are not trivial to launch by an end-user, but still can be downloaded and launched with some tricks. If you'll run into issues, ping me, I have a link to a step-by-step tutorial on how to run such build saved somewhere.
Now for the tricky part - iOS. Technically, you just can't distribute an iOS build at all. Apple Store does not accept adult games (at least the last time I've read something about that), and it's almost the only way to distribute any app to an iOS device. There are a few workarounds. First one is to have users download the XCode build and it (I guess, I didn't try, just heard of) can deploy the build to the device "for testing" (most likely they'll have to do very non-trivial manipulations for that, very likely they'll also need a developer certificate). There are also alternative ways of distributing iOS builds (through online testing platforms, e.g. TestFairy has some sort of a free plan, I guess?) - all of them require end-users to install some specific certificate on their devices and you make specific builds for their devices. This looks like - they install TestFairy certificate on iPhone, they follow a sketchy link and give ID of their phone to you - you go to Apple Developer portal and add this ID to your certificate - then you make a new build signed by the updated certificate, and then they can install the game from TestFairy. Note, I was developing regular apps this way - I don't know policies about adult content on that or other similar platforms. UPDATE: Ah, and surprise: you may only add something like 50 or 100 devices this way.