Visit your ApiOmat URL (e.g. https://studio.apiomat.enterprises) and log in. Once you have logged in, create a new backend if you have not already done so. Now navigate to the SDKs tab and click on the ApiOmat Studio box, and then click download.
Note, It is completely normal if the download may take longer than depicted in the GIF.
The download is a folder, which should be named "ApiOmatStudioMobile". Open the folder and double click on the file named "install.command". During the installation, the command line will appear. The installation is complete when the terminal shows "process ended" and you can close the terminal. The Gif below shows the installation process.
If you get a message that the software cannot be installed, as it is not from the App Store, go to settings, then security and click on the button to allow app downloads.