How to download and setup caffeine
Open terminal and run command
                                            git clone https://github.com/rehacktive/caffeine.git
                                        
                                        git clone is used to create a copy or clone of caffeine repositories.
                                        You pass git clone a repository URL. it supports a few different network protocols and corresponding URL formats.
Also you may download zip file with caffeine https://github.com/rehacktive/caffeine/archive/master.zip
Or simply clone caffeine with SSH
                                            [email protected]:rehacktive/caffeine.git