Unfair traffic offence (200€) (Broke student)

Hello, I am a broke student from Croatia, Living in Pula, currently studying in Rijeka, and while I was on my Way to Rijeka to see a Doctor, I was hit by another vehicle behind me Because of one vehicle in front of me that stopped suddenly for no reason and the police Said that its my fault which makes no sense but here we Are, offence is 2500 HRK which is ~300€ but if I pay in three days from now it will be 1250 HRK which is <200€ but gogetfunding says that 250€ is minimum. If you donate thank you in Advance. I dont need more than 250€ and that is the limit