I must be doing something wrong. DL'ed from the link to my sd card. Opened astro and pressed the apk to install it and got an error message saying it could not open as an apk file. Redownloaded and got the same message. Not sure what I'm doing wrong, I've installed other apk's using astro without any issues.
Edit: nevermind, for some reason the first two I dl'ed were incomplete, third time was a charm. I like the widget, but I wish it had the scroll bar that let's you skip between letters in the song list like on the stock player. Also not quite as smooth.