I have completely different hearing aids and computer(s) but my hearing aid manufacturer technical support recommends the exact same device for me. I have Oticon OPN S 1 (OPN 1 previously) - they are MFi hearing aids so communicate with iPhones correctly but need an intermediary device (ConnectClip) to communicate with the bluetooth in computers. Mine would not work with an iMac Pro (expensive desktop with built-in Bluetooth 5) but worked fine with an Apple MacBook Pro with Bluetooth 5. When I asked my provider, she called Oticon and they told us that we should always use the Sennheiser BTD 800 (one was shipped with my ConnectClip) with any desktop as many bluetooth implementations were either incomplete or buggy. Using the BTD 800 allows reliable streaming of audio from the iMac Pro to the ConnectClip and on to my OPN S 1 hearing aids when the computer is running either the latest macOS or Windows 10. One difference is my iMac Pro sits on my desk as it is an all-in-one kind of computer with everything built into the 27" display - the USB 3 ports are on the back but it works for me.
Kind of silly that apparently the drivers for Bluetooth are so buggy/incomplete in both Windows and Mac boxes but I gather Sennheiser ships the dongle with some of their bluetooth headsets. They also provide an update program that updates the dongle firmware (and they issue firmware update every so often).
Not an inexpensive device but I find it useful and if Phonak recommends it for you, then it might prove useful for you also.