If you have created a Community and find you can't seem to access it, you likely need to add yourself to that Community.

Under your Users tab in the Community dashboard, you can either add in your admin email address, or copy the unique invite link for your Community.

When you arrive at the login screen, just ensure that you log in as an existing user, rather than creating a new account. You already have an admin account for the dashboard, so logging in as an existing user ensures that your admin privileges carry over into your Community.