Monzo typically offers loans to applicants with high credit scores. It's important to note that your credit record is just one factor that Monzo considers. However, if you don't have a high credit score, you're very unlikely to get approved for a Monzo loan.
A "Good" or "Excellent" credit rating would require a score of 881 or higher if you're referring to Experian's scale, 531 or higher if you're referring to Equifax's scale and 604 or higher if you're referring to TransUnion's scale.