You can’t sort playlists from the streaming service (for now), although with Soundcloud you can view BPM and key before analyzing them with the console. Why can’t it be done? I do not know. Maybe for compatibility with other streaming services (Tidal, Beatport, etc.) that do not send BPM and key in advance.
You can get around this limitation by doing this: have the tracks in your Soundcloud playlist analyzed by the console, simply by uploading them to one of the Prime 2 players. When you have analyzed all your tracks, then you can switch between Soundcloud to your local collection on your stick USB (or whatever you use).
Now you can find your Soundcloud tracks in the local collection, and from there you can send them to a local playlist. At that point you will be able to manage that playlist like all the others and therefore also to sort them by BPM or key.