Using the Zapier integration for MMC, when using the 'When Contact Record is Created in Maropost Marketing Cloud' trigger, there is a required email field on that first step, but it's really not clear what email is to be used here (see screenshot attached)
Further testing shows that you should be entering an example contact's email address that is already in the MMC account, that will be used for the testing phase in creating the zap, but this is absolutely not clear.
Please adjust this integration to provide some information on this field:
*Enter an email address of an existing MMC contact for testing
