404 Error while Accessing sub directory

My directory structure:
base_url : /application/views/PGO
sub directories: /application/views/PGO/PRO & /application/views/PGO/PRO/Admin

public_html/.htaccess
RewriteCond %{HTTP:X-Forwarded-SSL} !on
RewriteCond %{HTTP_HOST} ^xyz\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.xyz\.com$
RewriteRule ^/?$ "https\:\/\/www.xyz\.com\/PGO" [R=301,L]


Question:
When I access https://www.xyz.com it gets redirected to https://www.xyz.com/PGO and loads default page index.php. When I try access sub-directories https://www.xyz.com/PGO/PRO or https://www.xyz.com/PGO/PRO/Admin then I see 404 error.
where am I doing wrong?