You can't install a random program. You need to go through the appstore for everything. There is no shared filesystem. Trying to export an image from a photo ed

You can't install a random program. You need to go through the appstore for everything. There is no shared filesystem. Trying to export an image from a photo editing app takes a couple of seconds just to build the list of possible target apps. Everything is not only gratuitously complex, but reminds you you're not in control. You're a guest in Apple's world, instead of Apple being there to serve you.