If you need to manually install Java 11 with the Wowza Streaming Engine 4.8.19 updater, the below link may be used:

https://www.wowza.com/downloads/WowzaStreamingEngine-4-8-19+4/jdk-11.0.13_linux-x64_bin.tar.gz

Please note: This was previously available in your Wowza Account -> My Downloads and will be restored soon