You can only import directly from a library, if the Mac is running macOS 12 Monterey. Importing libraries is not supported on Big Sur macOS 11.5 -the system version shown below your question.
The library you want to import must not be an iCloud Photos Library and must not be the same library you are importing to. If the library has not yet been opened on your current system, open it in Photos to upgrade it to Photos 7, before you try to import from the library. Also make sure the library is on a locally mounted volume with a compatible file system and not on a volume used for Time Machine backups.