This package is currently visible in the Package Manager in 2021.2 and above. To install this package, follow the instructions in the Package Manager documentation.
To install the package in a version before 2021.2, type in
com.unity.localization under “Add package from git URL” in the Package Manager.
Further information can be found on the forum here
This Localization package version is compatible with the following versions of the Unity Editor:
- 2019.4 and later (recommended)