This is the Fortify/Jenkins plugin. We have a stand-alone Jenkins environment (not connect to the internet) and I downloaded the Fortify/Jenkins plugin from GitHub. There doesn't appear to be any way to manually upload, since there is no .hpi/.jpi file to use. Note: the download was a .zip file; renaming the .zip file to .hpi didn't work either (got a "NullPointerException" in Jenkins).
The Fortify plugin is available from the GitHub releases, as well as directly from the Jenkins updates Artifactory repository. The zip and tar.gz contain source files. Admittedly, the hpi is missing from the latest (19.2.30) release on GitHub, which makes me think they are not using the standard Jenkins plugin release mechanism and something "broke". Grab it from the updates site.
You can manually install the plugin from the Plugins | Advanced page
Navigate to the Manage Jenkins > Manage Plugins page in the web UI.
Click on the Advanced tab.
Choose the .hpi file under the Upload Plugin section.
Upload the plugin file.
ps: I'd suggest clarifying your issue to say the latest (19.2.30) release on GitHub is missing the hpi file.