or to get more philosophical about it, here's a scenario:
* you buy and download a set of FLAC files from bandcamp -- this is a "digital download". it's just a bitstream.
* you save these files on a hard drive, a physical, digital, magnetic storage medium, or an SSD, a physical, digital, solid state storage medium. it is still unquestionably a digital download stored on a digital storage medium. still just a bitstream.
* now you burn these files onto a cd. a cd is also a physical, digital, optical storage medium. by any reasonable standard, nothing has changed. still just a bitstream.
* you give this cd to a friend. now he has it in a physical format.
* does the friend have the album "on digital"? if not, where in the chain of events did this change?