@dbp: somehow the Raspberry Pi Repository is not available from your Pi. This may be due to some downtime of the Servers. Trying the installer again after doing a reboot of Router / Max2Play should solve the problem.
My experience with Bluetooth with Amazon Echo – Now I got an Echo for testing 🙂
Saying: „Alexa koppeln“ (german for open bluetooth to start connection)
In Max2Play Bluetooth Addon: Scanning for Devices -> click on Echo-ECW -> connected!
Switch to Pulse audiooutput in Squeezelite and play somthing with Squeezebox Server -> running perfect!
Next I am trying for some Smart Home with homematic and control Squeezebox Server with Alexa 🙂