Using single-use passwords
From Planfix
When Two-factor authentication is enabled, you will need to enter a one-time password generated by a mobile app when logging in to your account.
Open Google Authenticator on your smartphone (which you should have already downloaded and registered for) Find the one-time password related to your account. Enter the one-time password in the window in the web version of Planfix.
Please note: each password is active for 30 seconds.
Useful information
To log in to the mobile Planfix app with two-factor authentication enabled, you must receive a one-time app password.