Admittedly, I did not know that, but just tried it out: You can pull out a link from the blue “Return Value” pin of the spawned tileset, and select “Add Cesium ion Raster Overlay”:
When selecting the resulting node, the Cesium ion Asset ID (2 for Bing Maps Aerial Imagery) and Token can be entered in the details in the upper right:
(I hope that someone who knows Unreal/Blueprints better will chime in here if this is the wrong way to do this, but it seems reasonable for me…)