cannot access admin of subsite -> err_loop "too many redirects"

Problem: I cannot create a viable subsite on 1 of my 2 WP MU networks.
After I create a subsite, I cannot access the Admin because an error page comes up: err_loop “too many redirects”

I think that this is because of how my web host put my 2 MU networks. I don’t know the correct terms, so I will describe or diagram it. One MU is inside of another. But they are not parts of the same network – the MultiSites are each a separate entity.

MU Network 1.com is fully functional.
MU Network 2.com main site is fine. Subsites have no CSS look and cannot get to admin.

Directory:

MU Network 1.com
– MU Network 2.com (-this is a level under MU Network 1.com)
– – cgi-bin (- -files and folders under MU Network 2.com)
– – wp
– – wp-admin
– – wp-content
– – wp-includes

– wp-admin (-files and folders under MU Network 1.com)
– wp-content
– wp-includes
-.htaccess
– wp-config.php
etc….

Questions:
1). Is this structure a problem?
2). Why can’t I create functional subsites on MU Network 2.com?
3). What could cause the “too many redirects”, loops, thing?

I would greatly appreciate any input. I am not WP backend literate. Obviously. (But I am trying to learn.) Please keep that in mind if you make suggestions or ask for information.

Thank you