I'm trying to install Sourcetree 2.7.6a on macOS 10.13.6. After getting to the Login to your Atlassian account step, I click the Use an existing account button, and get the following login dialog. There is an input field for email, but nowhere to enter a password. The big blue button is blank, and if you press it turns darker blue but otherwise does nothing. The "Can't log in?" link just lets you reset your password, but that's not the problem.