Edit in JSFiddle

function go() {
    map = L.map("map").setView([48.845, 2.424], 5);
    var lyrOrtho = L.geoportalLayer.WMTS({
        layer: "ORTHOIMAGERY.ORTHOPHOTOS",
    });
    map.addLayer(lyrOrtho);
    var mousePosition = L.geoportalControl.MousePosition({
        displayCoordinate : false,
        altitude : {
        		triggerDelay : 500
        } 
    });
	map.addControl(mousePosition);

}

Gp.Services.getConfig({
    apiKey : "essentiels",
    onSuccess : go
}) ;

var infoDiv= document.getElementById("info") ;
infoDiv.innerHTML= "<p> Extension Leaflet version "+Gp.leafletExtVersion+" ("+Gp.leafletExtDate+")</p>" ;

<div id="map"></div>
<div id="info"></div>

#map {
    padding: 5px;
    width: 100%;
    height: 300px;
    box-shadow: 0 0 10px #999;
}

#info {
    padding: 5px;
    width: 100%;
    height: 20px;
    font-family: monospace;
}