I would recommend all-zone Navigo Découverte Weekly Pass (€ 22.8 + €5 for new pass case) since your stay is withing the same calendar week. It requires a face photo (3cm x 2.5cm) and your name on it. Without these you can get a fine by inspector.
It's good from Monday to Sunday of the same week for unlimited rides on all metro, RER, city buses and Roissybus. All zones (1-5) pass will cover CDG airport & Versailles.
You can buy or refill the card at metro, RER stations, and CDG airport RER station ticket office (between 2C/2E or 2D/2F). Pass will be activated the first time you use it by waving it near the sensor pad at the gate.
You can read the detail here:
https://parisbytrain.com/paris-train-metro-week-pass-navigo-decouverte/
Edit:
Their website says Navigo Découverte is open to everyone; the regular Navigo card is indeed for Paris city residents only.
https://www.iledefrance-mobilites.fr/aide-et-contacts/passe-navigo-decouverte/quelles-sont-les-conditions-dobtention-dun-passe-navigo-decouverte
Somehow I always assumed it needed to be 'activated'; but what you guys said made sense since it's good only within a particular calendar week. It does not need to count days of use. It's a contactless card, so you simply wave or tap it on the sensor pad at the metro fare gate.
@ Victoria: since you arrive on a Thursday; if you decide to buy Navigo Découverte weekly pass make sure to buy it on your arrival day as Thursday (till 11:59 pm) is the last day to buy it for the same week. BTK, Navigo Découverte is not available for purchase or renew online. New card has to be purchased in person at the Metro/RER ticket office/window. Renew/reload old card can be done by either Metro/RER Navigo ticket vending machine (place card on the purple card reader); or at Metro/RER ticket office/window.