You'll be running your AR projects on either an Android or iOS device, so you need to ensure the version of the Unity Editor you are using has the appropriate Build Support plugin installed. For iOS development, you need the iOS Build Support module, while for Android, you need the Android Build Support plugin installed, including Android SDK and OpenJDK. This can all be installed by going to the Installs section of the Unity Hub application (it may take a while since several gigabytes need to be downloaded).

For iOS, you will also need the Xcode development tools since Unity builds an Xcode project. Then, you can use Xcode to install the app on the iOS device. In this recipe, we'll illustrate the process for Android phones. Then, in the There's more ... section, we will provide details regarding how to test and run AR apps on iOS devices: