Will installing Magisk overwrite my ROM or kernel?

[Android Central Question]

I have a custom kernel installed with the stock ROM on my Sony Xperia Z5 Compact. Now I want to install Magisk. I'm new to this but I've been doing some reading and I just want to make sure I understand it correctly.
If I start up my phone, enter TWRP Recovery, click install, and select the Magisk zip file, that will not overwrite my ROM or kernel or anything, right? It will just install Magisk?

Thanks