Hello,
I also had this problem, and managed to fix it. I had to copy/paste the patch.exe before it was deleted by the updater. It is downloading to Users\<USER>\Outerra\update\appdata Just have to run Outerra.exe and let it download the patch, and then Ctrl-C and Ctrl-V the file as soon as it finishes downloading and before it is deleted. It took me a couple tries.
Now that you have the patch copy, you can go into Program Files(x86)\Outerra and delete outerra.exe.
Running the patch.exe will now actually complete and you can run the game.
-Resik