The purpose of the 'communication management approach' is to document how the project team will control and manage its interactions with stakeholders. This includes detailing the methods and frequency of communication to ensure all parties are appropriately informed and engaged throughout the project lifecycle.
PRINCE2 7 Foundation guide on communication management.

The primary purpose of the Quality theme in PRINCE2 is to establish and maintain the processes and procedures that will ensure all products created during the project meet the predefined quality requirements.
This includes planning, assurance, and control of quality. The Quality theme focuses on defining and implementing quality standards that the project must adhere to, rather than dealing directly with broader organizational quality assurance or the project scope.
PRINCE2 7 Foundation handbook and other official documents.