Not all PowerShell Modules are published to the PowerShellGallery but are hosted on GitHub.
Download zip/tar or git clone repo to your disk. Open powershell admin console, navigate to installation directory. Launch InstallModule.ps1. Module is installed to C:\Program Files\WindowsPowerShell\Modules
Import module:
Import-Module Install-ModuleFromGitHub
To install module from [username]/[reponame], branch master:
Install-ModuleFromGitHub -GitHubRepo [username]/[reponame]
To chose different branch
Install-ModuleFromGitHub -GitHubRepo [username]/[reponame] -branch testing
Use -destinationPath to select different installation path.
Use -SSOToken to authenticate in private repositories. Default is anonymous authentication with access to public repositories.
Use -moduleName to change module name. Default is repository name.