@Christy2 I am not sure if right clicking "save as" is available when you are browsing through your listing pictures while the lightbox is open (such that the background is all dark while you scroll through the pictures). I haven't been able to do this in Safari or Chrome. However there is a way to get the original pictures uploaded onto the servers.
Using Chrome:
1) Go to your listing
2) Click on the cover photo
3) Scroll to a verified photo
4) Right click and choose "inspect"
5) You'll notice a highlighted link. That is the photo stored in the server:
So this photo's link is https://a2.muscache.com/im/pictures/6203f35b-88b3-47eb-87b6-b6ec8deb0ed8.jpg?aki_policy=x_large
You can now right click and save the picture.
But here's the part where you can get the higher resolution photo. Just change the x_large at the end to "xx_large" and a larger photo loads, for example this is the larger resolution: https://a2.muscache.com/im/pictures/6203f35b-88b3-47eb-87b6-b6ec8deb0ed8.jpg?aki_policy=xx_large
Maybe I'm over complicating things but so far this is the method I know you can obtain the photos apart from taking a screenshot (which lowers the quality).
These photos however, belong to Airbnb and copyrighted by them. Please don't use them for any other purposes.