La Defense is not in Paris. When you buy tickets of RER it is valid in some area called “zone”. La Defense is located in Zone 3, so Ticket+ are not valid.
Imagine R student travel pass
Transportation card:
If you want some information about transports possibilities:
If you want travel for a long distance in train:
How to get to the airport Charles De Gaulle?
https://www.parisaeroport.fr/en/passengers/access/paris-charles-de-gaulle/public-transport
How to go to the faculty from Paris downtown ?