This package requires third party extensions. They need to be installed the regulat way in <mediawiki>/extensions directory

Using git (in your mediawiki webroot):

git clone -b REL1_27 https://github.com/wikimedia/mediawiki-extensions-FlaggedRevs.git extensions/FlaggedRevs

Using Special:ExtensionDistributor on mediawiki.org

https://www.mediawiki.org/wiki/Special:ExtensionDistributor/FlaggedRevs

or

wget https://extdist.wmflabs.org/dist/extensions/FlaggedRevs-REL1_27-2723016.tar.gz

Add into LocalSettings.php the following line of code:

$bsgReadConfirmationMechanism = '\\BlueSpice\\FlaggedRevsConnector\\ReadConfirmation\\Mechanism\\PageApproved::factory';