Dear PJ16_03,
Greetings. Thank you for reaching out to Microsoft Community. We are glad to assist you.
As your description, l understand that you would like to check the Mutiple Authentication App version for all users from Azure Portal. As far as l know, the Authenticator app was installed by user side, so, admin has no permission or resources to check what version of Authenticator app installed on users' device.
In case l misunderstood something and you need further support, it is suggested to contact our dedicated team, go to the Microsoft Authenticator app forum or Azure Active Directory forum, click on both links, then sign in to post your concern. Experts will provide accurate and fast answer as they have comprehensive knowledge and experience.
Additionally, you want to check it from Azure Portal, so, you can also contact our experts by creating a service request via Azure Portal. Our online support may have permission or resources to check it from back-end side, do the following to get in touch with them:
- Select the ? in the global header, then select Help + support in Azure Portal.

- Select Create a support request. Follow the prompts to provide information about your concern. When you're satisfied that the support request is complete, select Create. A support engineer will contact you using the method you indicated.

Hope you can continue to enjoy our service there. l appreciate your understanding and cooperation.
Stay safe and healthy.
Sincerely,
Tammy | Microsoft Community Moderator.