Bard would likely have some literacy.

More likely would have been taught orally. A traveling minstrel type bard is unlikely to have written music. Learn the song from your master/other performers then adapt as you wish.

We actually have quite a few troubadour “songbooks” from the late middle ages/early Renaissance period, indicating that it was a useful resource for minstrels of the time.

If we’re getting into the Renaissance period, a professional musician would almost certainly be able to read; we have printed music manuals from the period for all kinds of instruments; for example, Arbeau’s Orchésographie is a primer on courtly dance music that we still read today.

I would doubt most bards could afford books until after the printing press (~1440). During the middle ages (500-1500) is after the fall of the western roman empire (470) where papyrus stopped coming in for about 600-700 years (1100s) before cheap paper from Spain. I think court musicians were a bit different in “class” someone traveling is unlikely to be bringing a lot of written stuff with them all the time unless they were a weirdo. Once cheap paper and moreso the printing press to allow cheap copying spread then so did literacy. So its hard to definitely say whether the average bard would be literate. I think at the start of the middle ages, no, but by the end of the middle ages, yes.