Using Amazon music to make a playlist is tedious and time consuming (making any playlist one song at a time is rather a dumb idea on any platform).
I have lots of playlists I can easily make in iTunes -- 100 tracks-per-playlist of random tracks from my large digital music collection. This takes one second to do in iTunes. I store them on the home server, so if I want to hear them on an Echo of any kind, I just play the playlist on a mobile device and send them via bluetooth of mobile device to the Echo device.