There are so many versions of IBM JRE/JDK available for linux machine at https://www.ibm.com/support/pages/java-sdk-downloads-version-80
Which version is available for ubuntu(to be specific ubuntu 20.04)?
Those are multiple architectures.
You likely want the "Linux on AMD64/EMT64T" download. To be completely sure, check the output of uname -m for "x86_64". If you're not sensitive to what architecture you're running, this is likely what you're using in the last decade.