How do I play a specific sequence of songs from my music library in a slideshow for a friend's funeral?

Download the songs and create a Playlist. Then use that to replay them in order.

Create, edit, and delete playlists in Music on Mac - Apple Support

If you have Keynote on the Mac it might be worth setting up the slideshow with that app and export it as a video.

Recent versions of Photos on Macs have lost the ability to customise background music and slide display time (or at least made it very difficult to do). It seems even worse on iOS devices.

So much automation to supposedly simplify the process but the end result can be horrible. In a recent slideshow that I prepared the default music that it used for "memories" was very inappropriate and the display time was way too fast.

Keith Barkley wrote:

Their user name has iPhoto in it...8^)

😂 The OP's profile indicates they're on Sequoia (as you know, no iPhoto there) ... but s/he hasn't answered the question.

I never use iPhoto or Photos to do slideshows. iMovie does a much better job, especially when you add a music track ... you can easily adjust the timing of any number of slides (individually or as a group) to match the music track. Export it as a video and you can play it almost anywhere.

If I'm just showing pictures by themselves, I prefer to use Preview (View > Slideshow).

Make sure to create the slide show and export it to the desktop and try it out. Some music might not play if it is protected.

You should also take the slideshow file on a separate USB thumb drive for belt and suspenders.

What app are you using ... Music ... Photos ... iMovie ... something else?

MartinR wrote:

What app are you using ... Music ... Photos ... iMovie ... something else?

Their user name has iPhoto in it...8^)

Yeah, it was kind of funny for a while. I think at one time there were about 6 different programs for creating slideshows: iPhoto, Photos, iMovie, iDVD, Keynote and even Garageband!

Ha ha, or even Powerpoint! (From someone who's done it ...)