What is Supported from Tiled?
Orthogonal maps.
Maps up to around 50×50.
Any tile dimensions.
Any amount of layers and tilesets.
Tiles from different tilsets in the same layer.
Tilesets can have margin and spacing.
What is Not supported from Tiled?
Tiles smaller than the initial map setup (Example: if you created the map setting the tile size as 64×64, that will be the size for all tiles placed).
Drawing Offset.
“Use transparent color”. If you want transparency, just leave the tiles with a transparent background.
Tile rotation.
Isometric maps.
Object layers.
Map, Tile and Layer properties.
How to Create and Load a Tilemap
Create the map in Tiled (taking care with what is supported, as seem above).
Save it as .XML in your Unity project Assets folder. When asked to save, just type .xml in the file name (Mac OS X users: see below).
In Unity set the camera as Orthogonal and adjust the Size depending on your game settings.
Drag the TiledMap prefab from the Project view into your project Hierarchy.