Go to Devices.

You can see the screenshots on the right.

Click on the refresh icon on column header to manually refresh the screenshots.

Click on one of the images to preview it in a modal.

You can change the preview resolution from bottom left corner of the modal.

Refresh the screenshot by clicking on the right bottom button.

Click on one of your devices.

Click on the camera icon on top right corner.

This action will open the same modal explained above.

Click on Actions tab.

Click on Take Screenshot button.

This action will open the same modal explained above.

Spinner will be displayed while the screenshot is loading.

Offline devices will appear on screenshot like below.

This thumbnail means that we could not connect to the device momentarily. Try refresh screenshot button if that occurs.

Notice that, this also may indicate this platform is not supporting the screenshot feature.