Just to add to this, you do not need java installed at all if you use the .exe launcher installer (for Windows, or .AppImage for Linux). The executable comes with its own Java and will always use that instead of your own. However, if you use the .jar launcher, then yes you will need Java installed on your computer.
Furthermore, deleting the cache will very rarely, if ever, fix any sort of problem - they're usually network related. We're not a trash-tier 317 server which has a plethora of cache related issues.
Common fixes for other servers simply don't apply to Zenyte - our client is OSRS based, and not a 2005 client which has been recycled by 20 different RSPS developers over the years (unlike the vast majority of private servers).