"Failed to download file" when attempting to run 1.18.2 on certain macOS systems

Since my realm hasn't updated to 1.19 yet - I do wish you guys would find a way to fix the delay on that pretty please - I need to use 1.18.2 to access it. However, when I go to the installations tab and set it up - as I have done before - I get this message after clicking 'play':
Failed to download file.
Error details: Couldn't select a valid version of the Java runtime to download.
I haven't seen this before, and the launcher seems to run 1.19 okay (I set up a test world in single player). This is a brand new MacBook Pro 2021, and a new installation of the game. I've tried various solutions like re-installing, restarting etc, with support, but nothing yet.