Install Drupal 8 with Virtualmin - Error 500

Reson 1 : FollowSymLinks

By default, virtualmin does not support Options +FollowSymLinks (on .htaccess).

Solution 1 : Recommended

Change the site Directives : Add FollowSymLinks to the options list
Your VM -> Services -> Configure Website -> Edit Directives
Add +FollowSymLinks to the Options

The directives file must be like :
<Directory /home/YOUR_SITE>
    Options +Indexes +FollowSymLinks +MultiViews
    ...
</Directory>

Solution 2 : If you can't change the

It must be replace with Options +SymLinksIfOwnerMatch .

Edit every .htacces files contains Options +FollowSymLinks, replace with Options +SymLinksIfOwnerMatch .

You can do this with shell command (ssh):
find /path/to/drupal -name ".htaccess" -type f -print -exec sed -i "s/FollowSymLinks/SymLinksIfOwnerMatch/g" \{\} \;