Picking up a rental there isn't complicated once you know what's expected. Bring your passport, your driving licence, and an International Driving Permit is highly recommended if your licence isn't printed in Cyrillic. Most services and local owners accept debit cards nowadays, and you typically put down a small deposit beforehand then pay the rest in person when you collect the keys. Double-check the insurance excess so you don't get stung with unexpected charges later. A full breakdown of requirements and costs for renting a car in Russia is available on this site
https://getrentacar.com/en-US/russia .