Missing some files when using swagger-codegen

Hi, Im new to using Swagger-codegen so forgive me if Im missing something obvious here.. when I use swagger-codegen (osx installed via homebrew), it "works" but its missing files (according to the readme). There is no "vendor" folder and there is no "autoload.php" script either, so I dont know how to load the libraries (if following the instructions in the readme). 

Am I doing something wrong? Or is the API that im pointing to incomplete or something? Im confused.