Admin Fitune is a web application, and there's no need to download it from the app stores.

If administrators wish to have direct access on the phone, they can download and save it to the home screen on any device

In Safari or another browser log in to the admin URL: https://admin.fitune.io/
At the bottom of the browser, tap on "Share."
Select "Add to Home Screen."
Tap "Add."

In Google Chrome or another browser, the business's URL: https://admin.fitune.io/
In the top right corner of the browser, tap the menu.
Select "Install app" or the option "Add to home screen."
Tap "Install."

In both cases, it should install the app on the home screen.