Can`t make sub-directoins in wordpress.

Hello.

I want to make my wordpressite to a multisite. I have don what is in this description.
https://premium.wpmudev.org/manuals/wpmu-manual-2/creating-a-network-to-enable-wordpress-multisite/

But when i come to choose between subdomain and subdirectoins the wordpress tells me that my installation is not new so i have to use subdomains. But i want it as subdirections. What to do?

What i want is this with my domain. outofthebox.no is a Norwegian site, And i want a site that is called this. outofthebox.no/english that is a english site. Can i putt a new wordpressinstal there?

In my mind i dont have to control both sites from the same dashboard i can login to both. But does anyone knows how to make this work.

Best regards
Morten