So you are installing a fresh 3.7+ ... is that right?
It's linux, so one could install via command line:
cd /path/to/moodlecode/admin/cli/
php install.php [ENTER]
and one will be prompted for same info as in forms setting up the site.
Takes nginx out of the loop.
Then it runs through setting up all the tables in the DB.
Install has to be from the same IP address that initially began the install.
Moodle caches right away ... so if did GUI and site just looks messed up ... no theme, go to admin/cli/ and run php purge_caches.php [ENTER]
Then refresh browser.
If having issues, please check nginx error logs for clues.
'SoS', Ken