The first time you set up your Tablo 4th Gen, you'll be asked to create a brand new account within the Tablo application.
If you forget your Tablo Account password, you can select the 'Forget Password?' button on the sign-in screen.
Enter your registered email address and select 'Send Reset Code'.
Check your the inbox of the email address you entered on the screen above. Enter the reset code and your NEW password, select the 'Reset Password' button.
Once this is done, you will be brought back to the Tablo sign-in screen. Here you can enter your email address and the new password you just created, and then select 'Sign In'.