Thanks for replying, but this wasn't helpful at all as the versions under that link are also 13.5.
I wanted to know, how I can update to 13.5.6 as I am still unfamiliar with MacOS.
Found the answer myself though.
1. Under Applications look for Rejuvenation
2. Right click, show package contents
3. Find the updater updater and run it.
Didnt corrupt the save file if anyone else is wondering.