It seems like your issue might be that you download a JDK and didn't place it in a common location, or add it to PATH / JAVA_HOME / etc. You can also use java.jdt.ls.home to set the path to the JDK.

BellSoft Liberica is a build of OpenJDK that is tested and verified to be compliant with the Java SE specification using OpenJDK Technology Compatibility Kit test suite. The distribution includes ...