SigParser provides a few different authentication options for users.
Microsoft 365 / Google
These two options work the same way. Users can sign in using their corporate credentials. If 2 factor is turned on then this will be enforced for the user. This uses a process called OAuth so that SigParser's application will never see the credential information and SigParser only gets a limit amount of information about the user (ie. username, email address, name).
For users who can't use one of the above options they can opt to create a username and password. This option is rarely used, especially by large organizations.
Username and password can be turned off as a valid access method for your account so that users can only use the OAuth Microsoft 365 and Google option.