Only front page works I am trying to set up a local server to try out drupal 8.1.3 and so far I was able to set up my profile and website but I cannot go to any pages other than the first page. (Welcome page, front page)

I have used the following link to install Drupal:

https://www.howtoforge.com/tutorial/how-to-install-drupal_8-with-apache-and-ssl-on-ubuntu-15-10/

Few things to note:


I'm not sure if I have CleanURL, tried to fix this issue but couldn't succeed I believe.
I have tried  multiple different approaches to fix issues like CleanURL, SSL connection, Apache2 (AllowOverride All) etc
I tried adding "?q=" and while this doesn't make the page crash, it just directs me back to the front page


Currently, I am playing around with four files to try to figure out my problem: ".htaccess", "apache2.conf", "drupal.conf" and "settings.php"

I want to be able to access the Drupal tools to modify the website and run it locally, I simply want to test Drupal, I wanted to share this because it may simplify the solution.

Some of the code that I have added while trying to fix my situation:

drupal.conf:

            &lt;Directory "/var/www/drupal"&gt;
                    Options FollowSymLinks
                    AllowOverride All
                    Require all granted
            &lt;/Directory&gt;


apache2.conf:

&lt;Directory /var/www/&gt;
    Options Indexes FollowSymLinks
    AllowOverride All
    Require all granted
&lt;/Directory&gt;


.htaccess:

RewriteBase /

# homepage redirect
RewriteRule ^$ /SUBDIRECTORY/index.php?q= [L]

# if directory or regular file...
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d [OR]
RewriteCond %{REQUEST_URI} =/favicon.ico
# stop here
RewriteRule ^ - [L]

# if a regular file in SUBDIRECTORY directory
RewriteCond %{DOCUMENT_ROOT}/SUBDIRECTORY/%{REQUEST_URI} -f
RewriteRule .* SUBDIRECTORY/$0 [L]

# Redirect everything to /SUBDIRECTORY
RewriteRule .* /SUBDIRECTORY/index.php?q=$0 [QSA]


settings.php:

$settings['trusted_host_patterns'] = array(
  '^127.0.0.1$',
  '^localhost$',
  '^www.example.com$'
  );


PS. I have tried both localhost and an example website url like www.example.com but it didn't help.
PS2. I am only using Firefox currently but I don't think the problem is with the browser.

I hope I was able to follow the question guidelines, I am really trying my best to make it a question "suitable" to the website, I am sorry if I made a mistake.

Edit1: I have rewrite already enabled.
I believe the problem was due to the location of my .htaccess file. (The main problem was the Clean URLs.)

My original location was /var/www/drupal/sites/default/files; after, I moved it to 
/var/www/drupal. The .htaccess file started to being read. Previously, it was not being read.

I hope this helps someone else! This also may not be the solution because I am having a different issue now.