Before logging into the Portal, make sure to add the packaging org (the org which contains the code for your AppExchange listing) to the AppExchange Publisher Console.
If you are having problems please refer to this doc
Log into Salesforce org connected to https://partners.salesforce.com/
Then sign into https://security.secure.force.com/sourcescanner/
Not a Salesforce Partner
If you are not a partner and if you need to book an office hours, send an email to firstname.lastname@example.org
This video demonstrates on how to book an office hours