To Import Subscribers in Starter Plan, follow the below steps: 

Step 1: Login to your account

Step 2: Navigate to the Lists section from the left‑hand menu.

Step 3: Click on the name of the list you want to add subscribers to.

Step 4: Click on Subscribers in the top menu.

Step 5: Click on Create New.

Step 6: Fill in the subscriber’s details and click on Save Changes.