Regardless, you don't have a choice! Please ask to delay! Make sure to do it in the right way.
If you're not recruiting in a specific recruiting channel, will likely get a few weeks at most (though it's possible you'll get months, please don't count on it).
However, it sounds like you're doing university recruiting, correct? In which case they will not let you postpone because you are interviewing with a cohort.
This is why I always advise people to be 80% ready before they apply!
Now, if you're timeline is short, the #1 thing you can do to get ramped up quickly is hire a coach. They are a time lever and will stop you from making all the mistakes so many candidates make.
Here's some additional reading to help: https://www.preplounge.com/en/articles/pitfalls-case-interview-preparation