Based on the previous comments under the original question where we excluded many basic sources of failure of Joomla installation, I am now giving the possible solutions or causes here. As I wrote in the comment: this is not a Joomla error or not an error derived from Joomla, but from wrong server configurations. It could be MySql or the http server itself, or from PHP. We cleared Mysql (correct credentials) connection problem, Joomla file permissions(755 for folders and 644 for files), and .htaccess file (it is in the root folder correctly), however:
On a well configured server a Joomla install is about 5 minutes not more.
The most common additional reasons for seeing 500 server error during Joomla installation:
1. mod_rewrite is not being loaded on apache. Solution:
sudo a2enmod rewrite
sudo service apache2 restart
If apache is not configured correctly, .htaccess will be ignored.
Another link for configuration: http://www.iasptk.com/enable-apache-mod_rewrite-ubuntu-14-04-lts/
2. simplexml module is not installed or not working in PHP
Solve it with for example:
sudo apt-get install php7.2-xmlor
sudo apt-get install php-xml and apache restart.
I'll update my answer with more possibility (if needed) as we move along with the install when the original poster is checking the above on his server.
3. More on configuring Apache for letting the server reading .htaccess :
Is the .htaccess File Being Read?
If you have an .htaccess file which is set up correctly, but you are still getting an HTTP 500 error, the problem might be that the .htaccess file is being ignored.
In order for the .htaccess file to work, Apache will need to be configured to allow it to run.
Check the website's main Apache configuration file. For the main domain on a server, this will typically be:
Ubuntu and Debian: /etc/apache2/apache2.conf
CentOS 7: /etc/httpd/conf/httpd.conf
For other domains being hosted on the server, the location and name of the file will vary depending on how the domain was set up.
Edit this main configuration file and find the block which pertains to the directory where you are adding an .htaccess file. For example, the default document root for the main directory will probably be:
Inside this block, look for the AllowOverride configuration. Set this to:
More info on this here: https://www.ionos.com/community/server-cloud-infrastructure/apache/how-to-fix-http-error-code-500-internal-server-error/
4. Timeout error. I do not think we should deal with that in this particular case.
5. if nothing of the above helps, you can still check the whole server setup against this good write-up here: