Please click the 'Sign in with a password' link in the pop-up window after you click 'Sign In' on the myOsmo page.
If you don't have a password or forgot your password, please click on 'Forgot your password?' link in the same pop-up window.
Once you create a password, your browser should be able to remember it, so you won't need to go back to your email to log into myOsmo.
For more information, please see our PDF guide to myOsmo.