IPS does not provide support for you installing/setting up Redis on your server. This is because the process is different depending on what operating system you're using (Ubuntu, Centos, Alma, etc) and if there is a control panel involved, etc. They don't know how you're setup to provide guidance. I would suggest starting with Google as a frame of reference personally.
In addition, it requires you to recompile PHP to include the PHP-Redis module... so you would have to do that as well.
Again... if you're simply running a single VPS server, I'm not even sure you NEED Redis. Setting up something just to set it up adds complications that you don't necessarily understand and also introduces more things that could break or go wrong. I would suggest you not simply add it just because it is an option that shows up as available.