Google Sites randomly sorts photos in carousels. With a few exceptions, we generally leave them as is. To download photos, please try this method on a Mac:

1. On Mac, hit Fn+F12 to bring up Chrome Developer Tool. (2)

2. Click on Network tab, then refresh the page. Object will get fetched as the page get loaded. 

3. Filter by img then click on the left panel to find the image you like, then Save As.