Hi,
SimBrief is a pre-flight planning tool. Much like the real-world flight planning tools it is based on, approaches and approach transitions are not included in the flight plan.
Navigraph Charts is an in-cockpit/EFB tool, meant to be used once you are actually in the cockpit. The typical flow would be to plan the flight in SimBrief, then import it into Charts and select your approach and transition as necessary based on what ATC assigns you.
Best regards,