v.16.3.17 for was released on the 29th of April 2020.
Please note that Tomcat 8.5 and Java 8 is required for this version, so please upgrade if you have not done so before.
If you are using the chat/push module then you also need to upgrade Tigase, for instructions see here...
Upgrade Elasticsearch to version 7.4.2, see instructions here...
After you log into the support center you can find the installer in the Documents - Installation files folder.
Please follow the instructions on how to upgrade here.