We would need to see your Appium logs to be sure but I am almost positive it is just a matter of the .app being signed or built incorrectly. It is correct that you need a “debuggable”/not for app store app to run tests, it also needs to be built for the correct device type. When building the app, the developer needs to choose if the build is going to run on a simulator or a real device. Unless it is distributed through the App Store or some sort of Test Flight like mechanism, and app built for running devices will not run on a simulator and vise versa. Check with your app developer to make sure they are giving you the correct build.