Ready made package.json & gulpfile.js (gulp)

https://github.com/BlackrockDigital/startbootstrap-freelancer

When I download this template, I have ready made package.json & gulpfile.js. How can I install all devDependencies? Should I use defaul construction for every plugin:

npm i [plugin_name] [another_plugin_name] --save-dev

or another quick command?

Shoud I begin work with

gulp init

?

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