If you want to access your Quicken account, you will find it quite easy. To start, either launch the Quicken software on your computer or go to the Quicken website if you want to perform a web-based login. Using the available Quicken ID or registered email on your account, log in to your account on the login page. You'll then be asked for your password. Be mindful to type in the right credentials; you might be able to recover it if you forgot your password by clicking on the “Forgot Password” link, which indicates that there is a possibility of password recovery.

When you have filled out your login information appropriately, click the button labeled "Sign In" for your account. If you have the desktop version of Quicken, as you sign in to your account, the software will make sure that your data is synced with your account. If you are accessing Quicken through the web, it means that you will be able to log in to your account from any computer with internet connectivity.
In case there are problems logging in, update your Quicken software because using obsolete versions would cause problems logging in. Also, check if you have changed your password or your Quicken ID, so you can use the new details. If the above fails, you can contact Quicken support.

More Info: https://resetquickenpassword.com/

More Info: https://www.resetquickenpassword.com/quicken-file-password-not-working/