All answers contain part of the answer. Let me try to combine all in one.
Quick setup "file browser" mode on freshly installed nginx server:
Edit default config for nginx:
sudo vim /etc/nginx/sites-available/default
Add following to config section:
location /myfolder { # new url path
alias /home/username/myfolder/; # directory to list
autoindex on;
}
Create folder and sample file there:
mkdir -p /home/username/myfolder/
ls -la >/home/username/myfolder/mytestfile.txt
Restart nginx
sudo systemctl restart nginx
Check result: http://<your-server-ip>/myfolder
for example http://192.168.0.10/myfolder/