This is installed already for Java
C:\>java -version
openjdk version "1.8.0_382"
OpenJDK Runtime Environment (Temurin)(build 1.8.0_382-b05)
OpenJDK 64-Bit Server VM (Temurin)(build 25.382-b05, mixed mode)
This part thinks it's missing as a pre-requisite (screen shot 1)
then when you try to install it says there is a later version there already a later version
* DataMaker 4.9.1 GA
* GTREP is SQL Server 2019
* Running on Windows 2019 server
A later version of Java was installed.
Needed to uninstall openjdk version "1.8.0_382" and then able to run GTServer with no issues.