This is a typical step for those organizations that prefer to build their Python packages from source for reasons of security or that need specific build options or just to be able to work with the very latest version. Source code for packages can be downloaded or cloned from locations like Github, Gitlab, etc.
This is a typical step for organizations that maintain a local repository of approved Python packages for enterprise use. This can be done by directly downloading the file, or else using pip or a similar package manager, such as conda.
You have a few options when it comes to obtaining Python packages for inclusion in your project, depending on whether you want to download a package to a repository, download source code from which to build the package, or just download and install the package in your project in a single step.
