I think I'm having the same problem. the details are:
In MC install page:
when I click install, "Hold tight! We're getting Minecraft ready for you!" pops up for half a second then goes back to the install page.
I can't change the install location in advanced, install button still does the same thing as before
still can't change location/path
It is automatically set to JAR launch option, can't change it back to native at all
it also says "Java was not found on your system. Please install Java and refresh.". refreshing doesn't work, and I can't reinstall java without an administrators username/password (I'm using a school-supplied MacBook air).
I do have java installed btw, i can play MC from the MC launcher itself just fine.