How do I get Enotifications?

My application was taken in at the California Service Center and yesterday I got a text and 2 letters regarding that they had received it. Does the e-notification come in another piece of mail or is there something I'm missing from the 2 letters that I received?

https://egov.uscis.gov/cris/Dashboard/CaseStatus.do

click Sign-up for Case Updates.

Create an account and add your Receipt Numbers to your portfolio. Then, turn on Mobile Alert On.

Thank you!