First fetch your floor data:

const floorData = await api.fetchFloorData(locationID, floorID);

Adding an annotation:

Convert your x and y points to latitude and longitude. In this example you can view the latitude and longitude in the console.

const xyToLatLng = MeridianSDK.mapPointToLatLng(floorData, {x: 5269.126531688274, y: 3824.493588695426});

To confirm we have generated the proper latitude and longitute, we will convert our lat/lng to screen X and Y points that we can create an annotation for and update the map with an annotation:

const latLngToXy = MeridianSDK.latLngToMapPoint(floorData, xyToLatLng);

meridianMap.update({
annotations: [
{
type: "point",
x: latLngToXy.x,
y: latLngToXy.y,
size: 32,
backgroundColor: "red",
backgroundImage: MeridianSDK.placemarkIconURL("generic")
 },
 ],
 });