If you already have an OTP authenticator app installed on your phone, use it instead of installing a second one. Otherwise, browse to this page using your phone or tablet and select the appropriate item below; they are listed in order we recommend. Yes, of course, you may just search for these in the app store on your phone too.
Android
iPhone / iPad
Once you have an authenticator app installed, click the option to add a new entry (Choose to add an “Other” account if you are using the Microsoft Authenticator). Now, scan the OTP QR code on the paper we provided. Yes, you can install these apps on more than 1 device. Just scan the same OTP QR code on both of them.