Integrage MIcrosoft Authenticator for MFA

Hi guys,
i have a question, kindly, I wanted to know if integrating Microsoft Authenticator with my application, to login with MFA, has some costs, or is it free? If not, what is the cost per notification? is there a site I can refer to? Sorry if I ask this thing here but I can’t find anything that clarifies my doubts.

Thanks

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