My brother gave me his old Macbook Pro to use since he is not using it so I would like to wipe his credentials and add mine. Please help

You should ask your brother to do this => What to do before you sell, give away, or trade in your Mac - Apple Support

Or if your brother is only loaning you the computer, then he should create a new admin user account for you to use in order to keep your data separate from his. Of course if he is only loaning the computer and doesn't want you to make unapproved modifications, then he will only give you a Standard user account meaning your brother will need to install any new software.

If the apps that need updated were purchased from the App Store, then only your brother will be able to provide the authentication since App Store apps are tied to the AppleID which downloaded & installed them.