I have installed the version of 'Extension:Flow' which is compatible with my MediaWiki(version-1.32.2)
'Flow' extension appears on the 'Special:version' page too ...in the 'Installed extensions' sections of my wiki.
But still, it does not runs properly and this error now appears-->
Fatal error: Class 'Pimple\Container' not found in C:\wamp64\www\wiki\extensions\Flow\includes\Container.php on line 5