To Register for Partner Exchange 2015 you must Login to your existing VMworld account or Create a new account AND Login to your Partner Central Account.
Login To An Existing VMworld Account
If you previously created an account for VMworld.com or registered for a VMworld conference, please use the same information to sign-in and register for VMware Partner Exchange.
Create A New VMworld Account
If you do not have an account, you can create one after you've logged on to Partner Central.
NOTE: This account will also be used on VMworld.com.