Once you have received your Magic Link, and are on the Event Home Page, you can now enter a Password if you would like to login next time you come back to the event:
1) Click on the red ! by your profile in the top right corner:
2) Click on Security:
3) Enter your New Password and click Save:
You can now login to your event using the same email you used to register (the email that you received your Magic Link with) and the Password you created from app.expopass.com/login.