Need a Multisite (which is subdomain of main site) & need the Network's site to be as sub-d

1) Created Multsite (sub-domain):

2) Installed Plugin:

3) Created Network (sub-domain):

4) Installed Plugin:

5) Mapped: the sub-site:

6) Converted the Mutisite to a sub-directory setup (previously: sub-domain)

7) Created a new sub-site under network:

8) ISSUE: when trying to access : unable to load, getting 404 error

Still lost!!

SUMMARY: Need a Multisite Network (which is a subdomain of main site) & need the Network’s site to be as a sub-directory.