This assumes you have the following installed on your computer and made available to your console/command-line:
git (see https://git-scm.com/book/en/v2/Getting-Started-Installing-Git) or git bash on Windows (see https://gitforwindows.org/)
node and npm (see https://nodejs.org/en/download/ and https://www.npmjs.com/get-npm)
yarn (see https://yarnpkg.com/lang/en/docs/install/)
Fork client source code repository if you haven't already done so (see Fork client source code)
Clone your client repository fork: $ git clone https://github.com/[your-fork]/impactoss-client.git
Inside your local repository install dependencies: $ yarn
(this can take a while...)
Build: $ npm run build
(again this can take a while...)