The link i gave you is for the actual GraphQL package - the one you include is a adapter to Neos.
In the link I gave you, the installation instruction reads
And, lastly, activate the corresponding routes: Settings.yaml: Neos: Flow: mvc: routes: 'Wwwision.GraphQL': variables: 'endpoint': 'test'
and you mostlike don’t need the
At least try and see if it solves your issue. And if it does, please submit a PR to the Neos GraphQL package that explains that needed installation setup