First off, it would be nice if you would do minimal formatting of your posts, in particular quote literally outputs etc. as described here. That really helps people more easily understand your problem and help you out.
Perhaps your web-browser automatically unpacked the archive.
You should make sure you only have one of these. If you want the directory in a different place, just move the directory where you want it. E.g., to move it to /opt, do
$ mv ~/Downloads/vassal-x.y.z /opt/
It seems an assumption of that script did not hold on your system. I’ve fixed that - try to re-download and re-execute. Pay attention to the possible options
$ ./integration.sh --help
Please be specific. Perhaps copy’n’paste exactly what you see between pairs of ``` (see here).
Please read the original post. However, the fix I just made should probably fix it for you if you did what the post says.
Yours,
Christian