OpenVSP should run on Windows without installation. Simply unzip the archive to the location of your choosing and double click vsp.exe.
If OpenVSP does not work on your installation, please report your problems to the mailing list.
Unzip the archive to the location of your choosing and run the vsp executable.
For Ubuntu 18.04, a deb package is available at the OpenVSP downloads page.
For other distributions, there are no pre-compiled Linux binaries produced at this time. In order to run OpenVSP on Linux, you must compile it yourself.
OpenVSP is available from the FreeBSD's port collection. Installation instructions:
$ cd /usr/ports/cad/openvsp (as root)
$ make install
$ portinstall openvsp (as root)
This will pull all the dependencies needed to compile OpenVSP. Then it will automatically fetch, compile and install OpenVSP in your system.