Download the zip file with the Theme (do not unzip). Check in your Arduino IDE Preferences dialog your project folder. Create in that folder a new theme folder. Copy the donwloaded theme to the new ...

There are two installation packages available: package_rakwireless_index.json is for WisBlock Core module support in Arduino IDE v1.6.4 or newer. package_rakwireless_com_rui_index.json is for RUI3 ...