Croatia Boat How Would I Travel From Paris To Zagreb, Croatia, Then From Croatia To Amsterdam By Train?

How would I travel from Paris to Zagreb, Croatia, then from Croatia to Amsterdam by train? - croatia boat

I travel from London to Paris to Croatia, then in Amsterdam. My plan is to take a ship from London to Paris, but how do I get from Paris to Croatia, then in Amsterdam. I need some kind Eurailpass? I looked at their website and apparently you need in countries that are linked to travel to?

Please help! Thank you!