Welcome! So i have just created a tutorial today, i have tested it as it 100% Works! No errors like couldnt find a working PHP7 Binary.. It works on 0.14.0 but you can change it by Modifying phar files :3. It also helps on openning a port on firewall.. Here's the Link: https://github.com/CaptainDuck/How-to-install-a-MCPE-PocketMine-server-on-CentOS-7-Linux
What does the server come installed with? Is this a turn key server setup with plugins, permissions manager, etc?