Open the MilkUp app and click on the Customers tab at the bottom. Click "S" icon for the customer you want to subscribe. This will display a list of products based on your selected categories. After selecting a product, you'll be directed to the subscription page. Enter the price and quantity, set the subscription plan (start and end dates), and choose the slot time (e.g., Morning or Evening) along with the days (e.g., Monday, Tuesday). Finally, click on the Update button. Your subscription will be successfully added, and the icon color will change to green.