How Agent's eXp cloud account connects to the eXp Marketing Center
When an Agent is issued a eXp Passport and logins in to eXpEnterprise.com they can click on eXp Marketing Center and the eXp Passport will automatically login. It is the same with https://www.expmarketingcenter.com
The eXp Marketing Center gets its data about the Agent for the Passport. There is nothing the Agent needs to do.