When pressing the save button on the top right you will be presented with 4 choices:

1. Save as PROJECT polygons

2. Save as CATALOG polygons

3. Save as DRAWINGS polygons

4. Only download the file

Option 1:

Use this one if all the drawings in your project describes the same area and all the drawings have the same origo

Option 2: 

The same goes here as option 1 but it applies if there is a folder structure within the project

Option 3:

This applies if the polygons only match up to this particular drawing

Option 4:

This option lets you download the polygons as a .xml file