If you want to use the Horizons AI app maker on a device other than a desktop, you first need to access your hPanel, click on Websites tab and then on Edit webapp:

Then, while inside Hostinger Horizons application, to edit using your mobile phone, click on the button "Switch to Mobile Device" in the top right corner:

For now, you can only use Horizons on your mobile phone to edit and visualize the live version results of your web app.