When looking into preferences, I see a message that states “You are missing the recommended Android SDK Tools. Install the recommended version in the Unity Hub.” Same thing with the Android NDK. I thought since I let Unity install both, I would have the correct versions. Where do I go to tell Unity to install the correct versions? Or, what version is it looking for, I can install them myself.
When you download via the Hub, you need to expand the components section and select them there.
For anyone else who runs into this, I was also getting similar errors. As @JeffDUnity3D pointed out, although (I think) I selected those components during install they were not included. I closed Unity and installed them via Unity Hub. I then went to the external tools settings in Unity and DESELECTED the checkboxes - one of them caused a popup to appear that it detected what it needed so I accepted the dialog, rebuilt, and it worked. I know this is kind of vague but if someone else if struggling with this issue I wanted to provide some level of guidance.