Drupal 8.x

Please help a total Drupal/PHP noob out. I'm a student modifying a site that my organization inherited, and the site keeps encountering an error every time I try to add necessary modules to the site:

Hi.

Have drupal 8 installed in a subdomain. outside of root like below.

Domain is our top level, mysite.com (non drupal)
subdomain is subdomain.mysite.com (drupal 8)

/var/www/domain
/var/www/subdomain

The drupal 8 site worked on localhost.

Transfered all to /subdomain folder. When I visit subdomain.mysite.com all I get is the log in block. If clicking the register/signup etc links they return 404. If I try ?=user/register is redirects to front page.

I have a recipe content. I have three different vocabularies to be selected from.

(Example
1. main ingredient,
2. Part of the world where the recipe is from .........and
3. type of recipe ....say drink or dessert or breakfast or whatever)

In my current node form, these three drop-downs get rendered one below the other..... and does not look quite good.

In Drupal 8.9.16 I created a custom module "example"

In example.routing.yml are the following instructions:

example.form_a:
  path: '/example/form-a'
  defaults:
    _form:  '\Drupal\example\Form\form_a'
    _title: 'EXAMPLE FORM A'
  requirements:
    _permission: 'access content'

example.form_b:
  path: '/example/form-b'
  defaults:
    _form:  '\Drupal\example\Form\forma_b'
    _title: 'EXAMPLE FORM B'
  requirements:
    _permission: 'access content'
 

I am using Drupal 8.x and I wanted to use javascript to delete an option from the list of options within specific pages, i.e., content type, using a pattern of their machine names, i.e., proxy_request, in case the user is not an administrator and I searched and found this code inside a post and I used it inside the project's themes->mythemename->mythemename.theme file, but that didn't work and I have several problems I want to know how to solve, as I searched a lot I did not find a solution