Java. Lang. Noclassdeffounderror: Could Not Initialize Class Java. Awt. Container

I am pretty new to Ubuntu and also new to this forum. Looking for some help.

I've been trying to install Impro-Visor by downloading the Impro-Visor_unix_10_2.sh file and running that in a terminal.

I then get the following error message:

Starting Installer ...
java.lang.NoClassDefFoundError: Could not initialize class java.awt.Container
    at com.install4j.runtime.installer.frontend.headless.AbstractHeadlessScreenExecutor.init(Unknown Source)
 ..... 
Could not display the GUI. This application needs access to an X Server.
*******************************************************************
You can also run this application in console mode without
access to an X server by passing the argument -c
*******************************************************************

I tried:

• Reinstalling Java
• Installing different Java versions
• xhost +local: which was a tip I found on the Internet

None of that changed the behavior. If I do use the -c option the script runs fine and Impro-Visor does get installed. However, it doesn't launch. The error log says:

java.lang.UnsatisfiedLinkError: Can't load library: /usr/lib/jvm/java-16-openjdk-amd64/lib/libawt_xawt.so

Does anybody know how I can solve this?
Many thanks for good tips.