A geolocated walk, instead of using a timeline to arrange audio, arranges it according to spatial points. It is usually broken into little packets of audio that are triggered by GPS location, although there are also non-tracking ways to trigger a walk in the same way.
APPS
Echoes has a free option (“community” membership). You can play walks using their Explorer app, and make walks through their Creator app. I found creating a little glitchy on my phone — it’s still in beta — but there is a web interface for Creator here that works smoothly: https://creator.echoes.xyz
In Echoes, you create a “Collection” (a collection of GPS points and audio tracks), draw your points onto a map (called an Echo), and upload a sound file (called an Element) for each echo. You can test it on the site, or publish it to the app.
If you want more help along the way, you can try Voice Map, which will pair you with an editor to help all the stages go smoothly. You have the option to put a price on your walk through VoiceMap. https://voicemap.me/tour/new?mode=walk
MAP + PLAYLIST
If you don’t want to deploy your walk via app, another option is to create a playlist (on Bandcamp if it’s your original audio, or say, on Spotify if not) and a map of a location that tells your walker when to play each track.
You could also use this option for walks that aren’t tagged to exact locations. For example if you wanted to use a grocery store, you could have tracks to be played by the dairy, at the seafood counter, in the checkout line, at the edge of the parking lot, etc.
Or a very dispersed map with some interpretive parameters, like: Play track one in a location where someone has fallen down. Play track two in a place that inspires you with a sense of dread. And so on.