What's the required version of Java for the LEM 6.3.1 linux64 agent installer?
Java is built into the agent:
Java Runtime versions for LEM Agents - SolarWinds Worldwide, LLC. Help and Support
However, you may need Java to run the installer, assuming this might be the error that you're seeinng:
JRE Libraries are missing or not compatible - SolarWinds Worldwide, LLC. Help and Support