I’m on OS X 10.9.5. I downloaded the Download Installer for 5.4.0f3 and opened the dmg. I then double click “Unity Download Assistant” and nothing happens. I do find Unity Download Assistant on the (Dock Bar? The bar on the bottom, whatever that’s called). I also find it in Activity Monitor, but it’s not responding. If I force quit the assistant and start it again, I have the same result. I have also tried deleting the download installer and redownloading, but the result is the same.
Additionally, if I try to go to “update” on 5.3.5f1 it says it’s up to date.