In case you want to use WordPress Multisite, use this link. The only difference between those installers is that WordPress Multisite one already enables multisite option (it is possible to do it manually if necessary).
The idea is to replace the previous installation with a new one. But you should not uninstall your current installation until you make sure the new one work as expected (I would suggest keeping a backup).
You have two options:
- Upgrade only WP: This way, you will get the latest version of WP (4.9.8).
- Upgrade the full stack: You would update all the components included in the stack (WordPress, Apache, PHP, MySQL...)
I've just checked you were using VM. In this case, instead of using the installer, you could migrate your data to a new WordPress Multisite VM.
I hope it clarifies things