Diy wedding ceremony music

I need ideas on something I can use (NOT youtube or Spotify please) to add the 3 ceremony/post ceremony songs we want to use and adjust them to very specific times for someone to play from a phone.
We are 2 weeks out and cannot afford a dj just for a short time, and we will not have service at the location of our ceremony, so it needs to be offline.
I just want something I can put together for the songs to blend nicely at the right time and have someone push play once and let it run.I have them downloaded from the youtube app, but they don't fade into each other the way I want them to at the time I want them to. Thanks!