run ./build.sh from command line under current directory.
Once the build script is run, the folder build_directory/updatesite/sgx-eclipse-plugin contains the update site. This is the path that needs to be provided to the eclipse while doing installation.
If the Intel(R) Software Guard Extensions (Intel(R) SGX) eclipse plugin is already installed to eclipse and to build and install a newer version, uninstall the old version and start eclipse with the -clean option.
Then try to build the new version of the plugin and install it in eclipse.