App is showing my sisters email

This makes no sense at all. I cannot add apps to a iPad that I bought new. When I try it shows my sisters email and wants a password. I borrowed a streaming service from her, but that was the only thing I’ve used her email for, now it is what pops up when I try to add a new app. I saw other issues like this that suggested going to the App Presences but I cannot even find that. Please help.