I tried the epub on my newish Android tablet with Bookreader It was e x t r e m e l y slow and only showed the text - I wondered if it had any tunes in it? Bookreader is pretty old and basic; I suspect it needs a newer app with better memory management.

Here on desktop the default document reader, Xreader, opens it but fails if I click on a song in the TOC. I installed Calibre (which had gone missing at the last OS version upgrade). In Calibre I see it does have tunes and looks good - apart from a few extraneous entries in the TOC.

I didn't dare download it to my basic Kindle Reader. It would convert to mobi, as you said, but the device often struggles with my newspaper.