Workaround that worked for me, March 15, 2021. In unity hub:
1. click the gear to get to preferences.
2. Click "Installs" menu on the left, in the now visible preferences window.
3. Change the "Install locations" to a path that you have access to. I created a new folder, /Users/my_username/Unity, then used that.

Now it should work.

Still not fixed

Unbelievable. Multiple issues on this and still not fixed.

Come on...this is RIDICULOUS. Any workaround to solve that?

This is a really annoying way of doing things, huge 10 GB download, then fail silently and delete the files. At least get an error message in the UI.

The workaround here might help someone if it's not related to admin privileges: https://forum.unity.com/threads/unity-hub-2-4-0-on-mac-os-10-15-6-catalina-fails-to-install-unity-save-unity-editor-folder-path.968550/

Unity Hub 2.4.0 claims it validates install location in its release notes, but the same problem still occurs: lengthy download goes first, then it silently fails and leaves a notion about "missing location" in the Unity Hub logs, because the Applications/Unity/ folder has been originally created by some other user than the current admin one I'm running.

As a workaround allowing Read&Write for my current user/admin group as well as "everyone" recursively for everything starting at Applications/Unity/ does help to fix the issue, but it's a bit tedious and a bad practice to just instruct users to go around elevating access for every folder whenever there's problems.

I ran into this issue in the spring but didn't have time to troubleshoot. Just used the direct Unity installer, if I remember correctly. Pointed all 20+ of our Macs to the resulting install location manually.

Now I have more time.
What's the update on this? Just ran into this issue again.
Is there a work around yet? Besides privilege management solutions cooked up by our IT department, I either need to have an admin do this or go the direct install route and still have just as much work to do.
This puts quite a large wrench in our workflow for software deployment and configuration.

As referenced previously, this issue dates back to at least January of 2018, probably even further.

This issue wastes tremendous amount of time, each time you try, you first download such big files only to realize after the download is finished that it was un-successful and everything you downloaded gets deleted silently from temp files.

they just need to ask for elevation of permission before copying installer. and its been pending for a long time see the linked forum-

https://forum.unity.com/threads/unity-hub-cannot-install-unity-when-it-needs-to-elevate-privileges-on-mac.514088/

Is there a good work around for this?