No, that's good. I thought you might have used proper password protection of your site as you noted that you tried inputting a username:password combo in order to gain access.
If you've used the WP internal Page password protection then log in to your WP Admin and check the page settings (Edit). Over on the right there should be a field for adding the password for the page and save the changes. You shouldn't need to enter a username to access the page on the front-end.. just a solitary password box should appear.