Its hard to tell with the limited configuration shown the exact problem you face but I managed to install phpmyadmin doing the following
My Apache configuration is setup in /etc/httpd/conf.d/laravel.conf
<VirtualHost *:80>
DocumentRoot "/var/www/html/public"
<Directory "/var/www/html/public">
Options Indexes FollowSymLinks MultiViews
AllowOverride All
Require all granted
RewriteEngine On
RewriteBase /
RewriteRule ^index\.html$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.html [L]
</Directory>
</VirtualHost>
Make sure you restart httpd service after making any changes
I downloaded the latest tar.gz file from phpMyAdmin, extracted using tar zxf phpMyAdmin-4.8.3-all-languages.tar.gz and moved to /var/www/html/public/phpmyadmin using mv phpMyAdmin-4.8.3-all-languages /var/www/html/public/phpmyadmin and was able to access the application using http://domain-name.com/phpmyadmin/