It seems that you have a failed installation on Mac, the UnityPackageManager should be present. Other users have reported the same issue on Mac ( **READ ME FIRST** Troubleshooting connection/loading project issues with Package Manager - #5 by Sommer )
Please try to reinstall Unity from the hub, and don’t quit the hub while the installation is happening.
I’m curious on how did you run into this situation, if you could provide more information, I would appreciate it.
Did you happen to quit the hub while the editor was installing? (Not while downloading, while installing). Or is it possible that you have an antivirus that quarantined and moved the file from its original location?