Maybe you are using Arduino IDE 1.x? The instructions I provided are for Arduino IDE 2.x
Anyway, just skip forward to the "B. Install variant of library with Nano R4 support" procedure and try proceeding with the rest of the instructions.
The reason I provided instructions for removing the existing installation of the library is that in some cases Arduino IDE will refuse to replace an existing installation when you use the Add .ZIP Library feature. However, that might not be an issue and the alternative of manually removing the library installation is somewhat complex. So I think it is best to just soldier forward and then deal with any problems if and when they occur.