What is the problem? Please be detailed.
The button to Download an XML file from ODK Build is cut off at the bottom of the screen so it is not available as an option.
What ODK tool and version are you using? And on what device and operating system version?
Macbook Pro Version 10.12.6
Chrome Version 61.0.3163.100
What steps can we take to reproduce the problem?
Create a form in ODK Build.
Click File > Export XML
The Download button is cut off at the bottom of the screen.
What you have you tried to fix the problem?
Scrolling down within the pop-up (doesn't scroll)
Clicking on the pop-up and moving it upward (doesn't move)
Resizing the browser window (doesn't work)
Anything else we should know or have? If you have a test form or screenshots or logs, attach here.