For Buddy to be able to update NGINX and run other commands as root, you need to follow these steps to give the user buddy access.

If no user has been created, follow the guide here to create a user for Buddy:
https://www.digitalocean.com/community/tutorials/how-to-add-and-delete-users-on-ubuntu-16-04

1. On ubuntu based systems, run " $ sudo visudo "
2. this will open /etc/sudoers file.
3. If your buddy user is already in that file, then modify to look like this:

buddy ALL=(ALL) NOPASSWD: ALL
4. save the file by doing Ctrl+O  (dont save in tmp file. save in /etc/sudoers, confirm overwrite)
5. Exit by doing Ctrl+X
6. Relaunch your buddy job 
7. you shouldnt see that error message again :)