Add app on Startup Ubuntu 18.04

Job ID: 33499785

Budget: $10 – $15 USD

Hi, I have a Linux app that needs to be started immediately on ubuntu loading.
The purpose of this app is to establish VPN connection. It must be run on startup without user logging in to the system.

Currently, I must log in manually every time for it to establish a connection. Note the app just needs to be started, it auto connects to the VPN.

I have tried on the several ways but none of them works:

1. crontab -e added this line @reboot su user -s /home/user/app
It runs on startup but only works if I log in to ubuntu
2. added it to Startup applications using GUI in ubuntu
The same thing only works after I log in to ubuntu

If you know how I can run this on startup without the need to log in to the system, please bid.

The budget is $10, looks like a fairly simple task.
Related categories: System Admin Linux Shell Script Ubuntu Debian