Data subject access requests

Imagine that you are an Australian startup that recently launched operations in Sweden. You offer a fitness app for mobile devices and still need to implement an automatic download data option. One of your users sends you a data subject access request in the middle of your summer break, but since you are a small team, you see it 20 days after the sent date.

You are now scrambling to ensure you respond to the request in time.

Which steps are not essential for processing this data subject access request?