You will get the link of slot booking on their official website itself i.e. amrita.edu.in 

To do the slot booking first login using your application number and date of birth, select the test date and slots based on the availability choose the date of your choice, click on continue then select the time slot for the exam and once you're sure about the date and time click on comfirm slot. The name and the address of the exam center will be displayed on the admit card.

Hope it helps.

Thank you.