With version 11 this program work well. In data we have longitude, latitude and a number that indicate a class. And this program draw a map with stations.

GeoListPlot[data[[All, All, 1]] , 
 PlotLegends -> data[[All, 1, -1, 1]], 
 PlotMarkers -> {Style["\[FilledCircle]", FontSize -> 20, Black], 
   Style["\[FilledDiamond]", FontSize -> 20, Red], 
   Style["\[FilledSquare]", FontSize -> 20, Blue], 
   Style["\[FilledUpTriangle]", FontSize -> 20, Yellow]}] 

But this program don't work with Mathematica 12. Why ? Only the map appear, but not the stations.

A. Dauphiné