Adding another user to console

Hello.

Is the user you are using to access the management console an IAM user?
In that case, I think you should create an IAM user by following the steps in the document below and attach an IAM policy that allows file uploads to S3.
https://docs.aws.amazon.com/IAM/latest/UserGuide/id_users_create.html

If you are an administrator, you can attach the IAM policy "AmazonS3FullAccess" to the IAM user, but if you are not, I recommend that you attach an IAM policy that focuses only on the necessary operations.
https://repost.aws/knowledge-center/s3-folder-user-access

I assume you are using IAM user for login, and have enabled MFA with Google (?) authenticator.

You can assign multiple MFA devices to a single IAM user. Refer to You can now assign multiple MFA devices in IAM for more information.

Or you can create another IAM @Riku mentioned.

As well as the other 2 answers you can use the same Authenticator token on more than one device by scanning the same QR code on another mobile.