You have received a WhatsApp video consultation appointment. Once you have confirmed acceptance of the meeting there is nothing more that you are required to do.
The consultant will simply contact you on the number you have provided at the scheduled date and time using the WhatsApp mobile app.
If not already installed, you can use the links provided below. There is one for Android and another for Apple devices.
Android
https://play.google.com/store/apps/details?id=com.whatsapp&hl=en_GB&gl=US
Apple
https://apps.apple.com/us/app/whatsapp-messenger/id310633997