You can link your Microsoft and Google accounts to your Applicant Tracking System via the log in page.
On the login page there are options where you can log in with Microsoft or log in with Google.

Logging in with Microsoft
To integrate your Microsoft account, click the log in with Microsoft option. You will then be directed to your Microsoft account to select the account you wish to link.

You will then be asked to enter your account password, and then your account will be linked to the ATS. The next time you come to log in, you simply click log in with Microsoft and you will logged into the system.
Logging in with Google
Similar to the option to log in with Microsoft, click the log in with Google button and you will then be asked to sign in to your Google account. First enter your gmail address.

Then next enter your password.

Your Google account will be logged against the ATS you then the next time you log in you can use the log in with Google option and will be logged in straight to the ATS.