The CD that came with the device listed RTL8671B, but it's not on Realtek's website. Instead the manual points you to:
https://www.mytechkey.com/pages/driver
4.Bluetooth 5.0 Dongle
Driver Link:
https://www.dropbox.com/s/gwo9lz777i82f70/BT5.0%20Driver.zip?dl=0
Hope that helps someone.
https://github.com/peteristhegreat/drivers-backup/releases/tag/1.0
Direct link
https://github.com/peteristhegreat/drivers-backup/releases/download/1.0/BT5.0.Driver.zip
Adding visibility to @carkrueger 's comment below
If you look here: https://www.catalog.update.microsoft.com/Search.aspx?q=realtek+bluetooth+1.6.1015 You will find now: 1.6.1015.3014 from 11.01.2021
Direct download link: http://download.windowsupdate.com/c/msdownload/update/driver/drvs/2021/02/0d13721d-7aa7-47cf-887a-f53bcd228a5e_04c173bad44cec04d528d260392958dc6e5bcec3.cab
for backup purposes: h**ps://web.archive.org/web/20210216175344/http://download.windowsupdate.com/c/msdownload/update/driver/drvs/2021/02/0d13721d-7aa7-47cf-887a-f53bcd228a5e_04c173bad44cec04d528d260392958dc6e5bcec3.cab
Direct download and the popup window for 1.6.1015.3014
didn't initially work. I ended up needing to right click the link and select Save target as
.
For it to work for me on Windows 10, I unzipped the cab file into a folder and then used Device Manager to look at that folder. Worked like a charm.
That would be 1.9.1038.3001 from 29/9/2021, specifically. It's also available from Windows update, check Steelywing's post above. Note that his link to 1.9.1041.3002 points to a different Realtek chip, which is probably "not working for some people". We want rtl8761b, which is not the same as rtl8761a, never mind something entirely different. You can go down the list in windows update to find the latest one, although this is a very tedious exercise as you can't know what chips are contained in each package without looking.. For the latest 1.9.10x driver versions: https://www.catalog.update.microsoft.com/Search.aspx?q=realtek+bluetooth+1.9.10*
Fortunately for us the very latest one 1.9.1038.3003 (20/2/2022) happens to be for rltl8761b. This doesn't contain the rtkbtmanserv bit you mention.
Direct link: https://catalog.s.download.windowsupdate.com/c/msdownload/update/driver/drvs/2022/04/de514c3e-c4ba-4f71-9c69-610474fc3f3a_ab5a6631b0c6e91c5d374105d19042f50ca28728.cabThis release causes crashes, get the latest .3004 instead.Now I'm nothing if not anal but clicking through hundreds of of versions to get the latest management server is bit too rich for my blood so easiest way is to grab the old 1.6.1015.3020 (26/4/2021) the guys are talking about earlier.
Direct link: https://catalog.s.download.windowsupdate.com/c/msdownload/update/driver/drvs/2021/06/5775f5fa-4094-4edf-a4e8-d3b809eed071_6ecc7e4a750ed4e1f90885d598a0d91c8c83f385.cab
So first install 1.6.1015.3020 and on top of that 1.9.1038.3003. Hey presto, shiny new driver.