I called Apple and got more info, sharing here as it may be helpful to others.
Primephonic provided a code for 6 months of Apple Music. I tried that code and Apple's site did not accept it. So, I started a free trial. Apple Support says an account can only have a single promotion, so now the Primephonic code cannot be used with my account. The only reason I started the trial is because the code didn't work in the first place, but that doesn't matter to Apple.
They confirmed that ALAC is not supported in the browser, which has no settings for audio quality.
Looks like it's back to Idagio...