You can download Summers Gone and My Friends Never Die from the official Odesza site. Another alternative is from their YouTube page, the download link is there in the description of both albums. I remember in 2014, I tried to download the remix EP of My Friends Never Die but the DL/link was removed.

I was able to download them from the official website, but that was a while ago so I don't know if that option is still there; also, you could just listen to it on this app:))

Both albums are taken off of iTunes as far as I know. You can listen to them over the app. Or you could get the cd and add it to your iTunes library.

I downloaded them from the ODESZA SoundCloud and added them to my iTunes list manually x)