opencart 3.0.2.0 cannot login to admin immediately after install

I installed opencart 3.0.2.0 for the first time; unable to login to admin using correct credentials. Login alerts username and/or password wrong.

The cart is functioning and I can browse the products, cart, etc.

I'm on shared hosting so limited root access. Details below if it helps:

Server: Localhost via UNIX socket
Server type: MariaDB
Server version: 10.0.32-MariaDB-0+deb8u1 - (Debian)
Protocol version: 10
User: opencart@localhost
Server charset: UTF-8 Unicode (utf8)

Web server

nginx/1.10.3
Database client version: libmysql - 5.5.58
PHP extension: mysqli Documentation

phpMyAdmin

Version information: 4.3.9

PHP version?