If you want to add the subscriber in bulk, follow the below steps:

1. Click on the Settings icon on the left side menu bar.
2. Click on "Manage Subscribers" under User Management
3. Click on "Import" button present on the right side of the page 
4. Click on the "Choose file" button to select the CSV file containing subscriber
5. Toggle the "Send subscriber verification Email" to skip the verification Email
6. Select the services which have to be associated with the subscriber
7. Click on "Import" button to add the subscribers