Changing your map on the Unturned server is quite simple to do. However, there are a variety of default maps you can choose from: PEI, Russia, Washington, Yukon and Hawaii.
1 Navigate to your game panel
2 Head to the file manager
3 Click on the Servers Folder > PterodactylUnturned > Server > Commands.dat
4 From there, type in Map (mapname). for an example, Map Yukon would be placed inside of that file.
5 You can click save & restart your server.
That is how you change the map on an Unturned server.