You’ll need a Windows or Mac computer with the iTunes software (NOT WEB), a CD burner and at least one blank CD. You also can’t have an Apple streaming subscription.

Once you’ve met the prerequisites, buy the album, download it to your computer using the iTunes software and burn it to a CD using the iTunes software. From there, rip the newly minted CD to whatever format you fancy.

That’s been the work flow since the beginning of iTunes and should still work. Admittedly, I haven’t tested it in more than 10 years.

As far as I know there isn’t a bypass available. Haven’t checked in a while though.

You may be able to simulate burning to a CD and burn to .iso instead, but I haven’t done that since Windows XP, so you’re on your own there.

Edit: forgot to add that you have to use the iTunes software to burn the CD.