This is a general tutorial on how to install Unity with Android Build Support. This is intended for those following my AR tutorials, but this works just as well if you just want to install Unity.
Download and install Unity Hub
Go to unity3d.com/get-unit/download
You will see two options. One is to install Unity only, second is to use Unity Hub. Download and install Unity Hub
Why Unity Hub?
Unity Hub allows you to manage and install addons and plugins easier. It will also help maintain multple versions of Unity. Why? Later on in your development life you will realise that unfortunately different people uses different versions of Unity for development. With the hub you can install their versions too, and access their project without screwing up your own project that uses your version of Unity
Installing the latest Unity in Unity Hub
Start up Unity Hub, you will see something like this. Press Add
Add Unity Version window appears, select the latest release of Unity and click Next
You will be asked which components to install. Make sure the options shown below are selected. Then, click Next
Unity will begin downloading and installing. Once done, it will look like this picture below.
That’s all on how to install Unity for Mobile Development