I need this internship bad

I’ve made it to the final round of a cybersecurity internship interview process at a large telecom/fiber company. This is the only interview I’ve gotten, and i will be a senior in college next year, so this is likely my one and only shot at an internship. I’ve been told in advance that there’s a HackerRank portion of the interview. I am notoriously poor at Leetcode/HackerRank style problems. What are some realistic, actionable things I can do to prepare for the interview in three days?