if you have desktop environment installed you can download NoMachine package from nomachine.com.
If your fedora does not have a desktop environment installed, you must install it first before installing NoMachine.
There are several options for downloading the package without desktop.
Install wget and download the package from the site using these commands.
yum install wget
Or download the package from the NoMachine website to your computer, then send to DigitalOcean using the scp command.
scp nomachine_6.9.2_1_x86_64.rpm firstname.lastname@example.org:~
x.x.x.x is your Fedora IP
How to install NoMachine form console you can find in this article