Multisite Network Admin Redirect Loop Problem

I’m new to WordPress and this whole Multisite setup, and I am trying to access the Network admin panel. I did get it set up using a subfolder (not subdomain) setup, but when I try to access the panel, it tells me:

The webpage at https://www.ucan.io/main/wp-admin/network/ has resulted in too many redirects. Clearing your cookies for this site or allowing third-party cookies may fix the problem. If not, it is possibly a server configuration issue and not a problem with your computer.

I have the following items in my wp-config.php file:

define( 'WP_ALLOW_MULTISITE', true );
define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', false);
define('DOMAIN_CURRENT_SITE', 'www.ucan.io');
define('PATH_CURRENT_SITE', '/main/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);

and my .htaccess file:

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
# uploaded ?les
RewriteRule ^([_0-9a-zA-Z-]+/)??les/(.+) wp-includes/ms-?les.php??le=$2 [L]
# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]

I tried to follow several bits of instructions to try and fix the problem, including this one.

But for whatever reason, when I tried to follow the instructions, there were no domains showing up on any of the lines!

All plugins are disabled, I’m on the default 2015 theme, and I’m stumped…

Does anyone know of a solution that will allow me to access my network admin panel for multisite?