There's no way to actually know what the credit score would have to be at minimum for quicken loans to approve your loan.
But most loans require you to have at least 600 or higher credit score before the loan would eve be considered.
You could try applying for the loan with a lower credit score but you would probably just get turned down.
If your credit score is 600 or above then you'll have a better chance at getting the loan from quicken loans.