Rule #5 states: Majority of the game must be made in the 48 hour time frame.

what sort of assets not made during the jam are allowed, just stuff you made or anything you have permission/licence to use and is it required to specify what parts of the game were made duroutside of the jam?

You can use any asset that you have the right license to use even if the assets were made prior to the jam. the levels and the gameplay should be made during the game jam