How do would you tackle two conflicting views from two different internal customers. How would you tackle a situation where a customer wants something complete

How do would you tackle two conflicting views from two different internal customers. How would you tackle a situation where a customer wants something completely diffrrent, which you are made aware of during UAT. What is a customer journey? What do yoh thing of working agile? Hiw do you start off after being hired onto a project and broader system ecosystem you have never been part of before.