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To clone a repository you can simply take the url give by the web ui:
Than git clone in local:
git clone <url>
If the repository is this https://github.com/mkdocs/mkdocs, you can copy that git url and clone with this command:
git clone https://github.com/mkdocs/mkdocs.git
To install you can follow this guide: https://www.mkdocs.org/#installation
Hope to solve your problem 😊
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