Before you connect this Logitech keyboard to Microsoft Windows or Mac PCs, you need to download and install the Logitech K400r driver package. It has supported by Setpoint app which gives you full access to control the K400r wireless touch keyboard and make custom settings as needed. Here you can free download the latest drivers and software for Logitech K400r.
Logitech K400R Driver and Software Downloads

Supported Driver for Windows OS
OS Compability: Windows 11 (32-bit), Windows 11 (64-bit) , Windows 10 (32-bit), Windows 10 (64-bit), Windows 8 (32-bit), Windows 8 (64-bit), Windows 7 (32-bit), Windows 7 (64-bit).
Software Packages
Firmware Update Tool, Setpoint, Logitech Unifying.
Supported Driver for Mac OS
Specifications
The Logitech K400r is a handy little Wireless Touch keyboard, it runs on two AA batteries which it actually comes the keys and the track pad are quite soft. Plus the K400r keyboard is actually compatible with a huge amount operating systems, including Windows, Macintosh and Chrome OS.
Related Keyboard: Logitech K750 Driver Download
This has supported by Logitech Unifying Receiver technology which allows you to connect multiple Logitech devices to your computer or laptop with just one receiver. But you need to install Logitech Unifying software first. Download Logitech K400r drivers from Logitech Website.