RER tickets are sold point-to-point or station to station (and Paris is considered as one point). The typical CDG to Paris fare is 10.30€ but you are going beyond Paris, expect to pay a bit more. I have no idea where the website you linked came up with 11.40€.
Consider taking a VTC (Uber, Kapten, Snapcar, or Bolt) from CDG to your hotel. What appears to be happening now in Paris is that as drivers work with more than one company, they may accept you as a Uber customer, receive a better offer from a Bolt customer, and cancel you before they arrive.
Itīs not clear what your travel objectives are beyond reaching this hotel but if Paris is your objective, you will have some serious transportation costs commuting from city to hotel each day, not to mention time involved.