Essentially all of the responses you will receive here in the Microsoft Community do NOT come from Microsoft. People who are identified as a "Microsoft Support Engineer" are employed by a third-party company that contracts with Microsoft to supply support services. The rest of us are just users of Microsoft products who volunteer to help others.
As near as I have ever been able to determine, Microsoft does not provide user manuals for its keyboards. Sometimes -- rarely, in my experience -- you'll be able to find a one-page pictogram that may describe what some of the features are.
Once you install the software for the product (Mouse and Keyboard Center 2.7 --> https://www.microsoft.com/hardware/en-us/d/wireless-comfort-desktop-5050), you should be able to access a help file that may answer your questions.
These "how-to" links may possibly help --> https://www.microsoft.com/hardware/en-us/support/how-to
Otherwise, if you have a specific question, ask it. There may well be someone in the Community who has one of these devices -- or one similar to it -- who knows the answer.
You could try the Microsoft Hardware Support telephone number 800-642-7676 (which, of course, is toll-free only if calling from the U.S.), but the most you should expect from this is an answer to a specific question about the product and not a User Manual.