Hi,
Check the following topics:
Installing Capella vs Capella Studio and the need for JMV - Capella - Eclipse Capella Forum (mbse-capella.org)
Capella Studio 6 and higher are (not free)? → Java 11+ is not unfortunately - Capella Studio & Kitalpha - Eclipse Capella Forum (mbse-capella.org)
So basically just download a JDK from JDK Java Net and add it to the PATH environment variable of your system. I recommend a JDK older than JDK 17 (Like JDK 11 or 16) because of a deprecated feature (Ant SecurityManager) that won’t allow you to build stuff.