Filemaker Go's file system is a bit different from Filemaker Pros. It also uses a few smarts of its own which you will see at the bottom of the file browser.
if (get(systemplatform) = 3
export to get(desktoppath...) & the filename plus the extension
export as usual
Filemaker Go manipulates its own desktop and if you use a custom dialog box to show Get(desktoppath) you will see how 'unusual' it is.
However, once it's in the Filemaker desktop, I wonder what you will do with it.
If you need to have this text file saved to a client's computer, that's an entirely different situation, although you could email it. Don't forget to use some common name that will be overwritten or else you will soon run out of disk space on your IOS device or have to delete manually hundreds of small or big text files.
If you want to export from Go to a windows computer or bootcamp, you'll need the remote pathname which would include something like 192.168... or an Internet Address plus other filepath info.
It might be easier to connect to the Filemaker Pro file and push the data into a field there and then run a script in the Pro file to save to disk as usual. You can perform a script in a remote file after selecting the Remote file name in the popup...