The folder contains various components and sensors: Arduino Uno, Mega, Nano, etc. We also have the written step-by-step adding and a download link.
Below is a video that will take you through a step-by-step process on how to add these libraries into Proteus 8.12 professional.
In order to simulate these sensors or components, you have to install them or add them to the Proteus library. Today, Proteus 8 professionals can host a variety of sensors and other components that are not in the Proteus database.