On Confluence cloud, as a result of the recent gdpr changes, your email id is not accessible to our app by default. Consequently, you will not receive any notification by email when you are added as a reader for a read request. In case, you would like to get these email notifications, you can follow these steps -
Go to the profile and visibility section of your cloud account.
Scroll to the bottom of the page to the Contact section.
In the drop-down next to your email id, select Anyone.
That's it. Now you will start receiving read request notifications in your email.