Macbook Air installing apps through itunes?

Question

iTunes

Tell me, does anyone know? they gave me a poppy beech air, an old one. I'm trying to install the application through itunes, it downloads the ipa file, I can't understand how to install it? I searched on the Internet like there should be a sidebar where you specify the device. I do not have such a panel, and there is no place to turn it on. Isn't this laptop designed to install an application from itunes?