Thank you. Now it works but the performance is not good when visualising the Strava heatmaps on detailed levels in other coordinate system than web_mercator. That was the strength of ArcBruTiles in earlier versions.
Viewing post in ArcBruTile 3.0 released comments
ok good it works now. In version 3 ArcBruTile is rewritten to the add-in plugin model, using more standard functionality and less custom made. Kinda forced by limited possibilities in recent ArcMap releases. It has some pro's and cons. Unfortunately had to leave the nice reprojection code behind. :-(