The Package Manager can load a package from a Git repository on a remote server.
PATH system environment variable.
package.json file respects Semantic Versioning rules with regards to officially published releases of this package. More info
To load a package from a Git URL:
Open the add menu in the Package Manager’s toolbar.
The options for adding packages appear.
Select Add package from git URL from the add menu. A text box and an Add button appear.
Enter a valid Git URL in the text box and click Add. For more information about how to construct a valid Git URL, see Git URLs and extended syntax. Unity supports several Git protocols and some custom or extended syntax.
If Unity was able to install the package successfully, the package now appears in the package list with the label. If Unity wasn’t able to install the package, the Unity Console displays an error message, such as:
Click on an error message link to get some help for it on the Troubleshooting page.
Tip: If you want to check for updates and update your Git dependency to the latest version from the repository, click Update. You can also use the Add package from git URL menu item to update your Git dependency. For information on Git dependencies, see Locked Git dependencies.