I'm stuck on next steps when attempting to configure a D365 for Marketing trial. We currently have a marketing application in an unconfigured state on the admin portal, and an existing D365 trial instance (which MSDN states is needed). When I get to the setup wizard I cannot proceed further. I don't know what else to do to proceed?
ISSUE 1: If I try to put in a brand new portal name for my webpage, I receive this message "No portals are available for your selected D365 organization"

ISSUE 2: If I first configure a portal with a unique name, then GO BACK to configure Marketing with that new portal URL, I receive this message "Your selected portal name is already in use, please choose a different one"

Am I missing a critical step during the setup? Very frustrating how hard this is. Any advice would be greatly appreciated!