It seems like Facebook has detected that you are trying to enable two-factor authentication from a device that is not familiar to them. This security measure is in place to protect your account from unauthorized access.
To address this issue and be able to enable two-factor authentication, you may need to use the device you are currently using for a while to establish it as a trusted device according to Facebook's security protocols. Once the platform recognizes your device as safe, you should be able to make the desired changes to your account settings.
Remember, two-factor authentication is a powerful tool to enhance the security of your Facebook account by requiring an additional verification step beyond just your password. It’s worth the effort to ensure your account and personal information are safeguarded.