Pacing someone
You don't need an account. Your runner sends you one link: how far along they are, about when they reach you, and, if they allow it, a way to talk to them before you meet.
Before you join
The link shows how far along they are and about when they reach the next aid station, so you know when to be at the handoff.
Before you start
If your runner's link allows sending, record a voice note, up to five minutes, and it reaches them on the trail. Tell them you are on your way.
All night
Everyone with the link hears the same voice notes, so you walk in knowing what the crew has been telling your runner.