This library provides a way to install bundles via CLI command. It is a replacement for bin/console pimcore:bundle:enable which got removed in Pimcore 11.
To install a Pimcore bundle you can execute vendor/bin/pimcore-bundle-enable BundleName. As BundleName please use the name which you see in bin/console pimcore:bundle:list.
In Pimcore 11 your config/bundles.php will get edited according to Pimcore documentation.
The command is also compatible with Pimcore < 11. In this case Pimcore's bin/console pimcore:bundle:enable command gets executed.