The Amazon Echo is a Bluetooth-enabled speaker and voice-command device. You may be able to stream audiobooks from the OverDrive app to an Amazon Echo, like you would with any other Bluetooth speaker. However, OverDrive does not officially support streaming audiobooks from the OverDrive app to the Amazon Echo at this time.
For help using Bluetooth with the Amazon Echo, please check out Amazon's help article about pairing your mobile device with Echo.
If you need any further help with the Amazon Echo, we suggest contacting Amazon support.