Mostly depends on how you create that backup.

What you can do is to setup Droplet with same OS as your NAS (if that is possible).
Install all needed Web server packages (e.g. Apache, MySQL...) and copy all config files you change. Make sure you needed create MySQL users.

Then copy WordPress installation and verify privileges. When you go to IP/domain you should see it.

If you specify backup method used we can help you with it. But if you just backup WordPress files, you must install LAMP/LEMP stack and configure it

Hi again.

I've looked at that plug in and as far as I understand it backups WordPress. It'll backups posts, pages, probably config that can you restore later when needed.
It's OK but it will not setup Web server and everything needed for WordPress.

To host WordPress or any other Web site, you need Web sever. You can choose between Apache and Nginx. Beside it, for WordPress you need PHP and database to store informations - MySQL.
That plug in will not install and configure for you, so you have to do it yourself.

We will try to setup WordPress using this plugin. I never used it so you will have to find out how to restore once you have working WordPress.

You have two possibilities:
1) to use WordPress One-Click App.
It'll setup you WordPress completly.
After you spin Droplet on it, login on SSH to activate WP. Then go to your Droplet IP and do initial config.
First install theme and plugins you had then install backup plugin and restore backup you made earlier.
2) setup LAMP/LEMP and WordPress manually.
I would recommend going with LAMP as it' more compatible.
How to set up LAMP.
How to set up WordPress on LAMP.
Now continue with config, setting up plugins, all like in previous solution.

Hope that it works. If it doesn't help you, you have another solution, to copy all files manually, and database also but I'll write it if needed.