I recently migrated from GoToTraining, which had a main dashboard where I could add quizzes, polls, surveys, documentation, etc to my Library. Then I could apply those to any training session I wanted. That doesn't seem to exist in the new GoToWebinar dashboard or am I'm missing it? Can I go back to the classic dashboard at all?
I'm afraid GoToWebinar doesn't have 'Materials' functionality like GoToTraining does: https://support.goto.com/webinar/help/share-handouts-during-webinars-g2w020025
Do you know if that's on the roadmap for GoToWebinar? We migrated from GoToTraining to GoToWebinar because we were told it has the same functionality (obviously not your problem).
I'm not 100% sure when all the features will migrate over, though you will see new releases updated here as they become publicly available.