I was also getting the same error.
nginx: [emerg] bind() to [::]:80 failed (98: Address already in use)
and when i typed the localhost in the browser, then i was getting
This is the default web page for this server.
The web server software is running but no content has been added, yet. instead of nginx welcome page, apache2 is running on the same port,
find the apache2 ports.conf file
change the port other then
80 , i make it as
save the file
restart your system
it will works for you also, if you type the localhost in the browser, you will get nginx welcome page