This means that the libraries were not updated properly. Try to reinstall B4A and make sure that no library is left in the internal libraries folder after you uninstall the previous version.
You just need to call RingtoneManager.Play with the uri you previously got with GetDefault or from the picker.
I uninstalled and re-installed in a different folder.
Now when I try to compile I get the error
Compiling generated Java code. Error
B4A line: 68
rtm.Play(URI)
javac 1.8.0_25
src\b4a\example\main.java:456: error: cannot find symbol
_rtm.Play(processBA,_uri);
^
symbol: method Play(BA,String)
location: variable _rtm of type RingtoneManagerWrapper