These are usually scams. There will be a text file pointing you to a website where you have to fill a survey or give some payment information to get the password. ( The file itself is usually genuine though). You can fine .rar password crackers online ( you can search in google for password crackers for rar files). Usually if it's a small file, they can crack the password in a day or 2, but it's hopeless for the such large files.
Bottom line is, you have to find an alternative link to download the game.