Jiglu uses the Java 11 platform. Either OpenJDK or the Oracle JRE will work fine depending on your preference, though OpenJDK will already come with most Linux distributions.
On OpenSuse use:
zypper install java-11-openjdk java-11-openjdk-headless
You may also need to install fonts so that the captcha images work:
zypper install fetchmsttfonts
On Amazon Linux 2 instead use:
If it was already installed you may need to check the correct JRE is set as the default:
update-alternatives --config java
Java, JRE, Linux, OpenSuse, OpenSuse use
Which Java to install and how.