Creating an event through Webhooks by Zapier

I am trying to create events based on the data from the third party app (booking platform). The goal is to trigger an event in Klaviyo every time a customer books a class through the booking platform. I am using Webhooks by Zapier, and while the test trigger works well, I am getting stuck on the Klaviyo step once the automation is launched. I am facing an error  “ the email address is missing”, however, the third party app sends the required data on the email and the event ID. 

On the Zap setup: 

On the error: 

Could someone share their view on this and what’s possibly can be wrong? 

Many thanks!