I am having the same difficulty. I can get to add device, however the only options are subwoofer, 2 or 4 speakers, headphones, remote. Phone calls to Amazon and Roku did not help.
Thanks for the post.
We would recommend taking a look at the information provided by our Support page here: How do I connect a Bluetooth® device to my Roku® audio device?
Please keep us posted what you find out and we will be able to assist you further.