Subdomain and subdirectory question

My website host have a service where if I use a directory it goes automatically as subdomain.

So for example, for http://www.mysite.com/wp I can, as well, use wp.mysite.com.

I'm trying now to install Multisite, but it's confusing because I am practically using subdirectories, but they're are used as subdomains, and in my WP options I use a subdomain, not a subdirectory.

What should I do about this here in this tutorial:

https://premium.wpmudev.org/manuals/wpmu-manual-2/creating-a-network-to-enable-wordpress-multisite/

in the step "Setting up your sub-domains or sub-directories"?

Thank you.