As already said, the Alex Crostini 1.1 were mounted with Big Apple on the Birdy Rohloff.

You also need other inner tubes, the one for the 40mm wide Marathon Racer aren't compatible with 50mm wide tires (from Schwalbe its the SV5A).

The only thing you might need to do is remove the thick plastic washer placed between the front mudguard and the fork (on the front fastening of the front mudguard, its a bold inserted from the inside of the mudguard that goes in a threaded hole of the fork).