Most of the core process for the Scrapebox Harvester consumes CPU, so I'm not sure why Loopline is talking about RAM, but he's certainly a pro.
Some of the Addons shift into RAM a lot more than CPU, so maybe that part of Scrapebox uses RAM more than CPU... not sure... but I guess you'll find-out.

What I would say, though, is your problem isn't necessarily the server itself, but rather the biggest issue Scrapebox has, in general, which is
threadlocks.
According to support, that actually is a problem with how Scrapebox interacts with the Windows API.
There are many thousands of threads available from Windows, but a single instance of Scrapebox taps into somewhere between 200 to 500 connections on average, depending on the feature you are using.
So, it's probably like LL says, where you will wanna run a bunch of instances, and see what you can manage to pull at-scale, since some of those will inevitably freeze from threadlocks.

As far as your machine goes, I no longer use VPS services, but rather purchased refurbished machines from Ebay.
I like the HP Elitedesk 800 g1, which ideally comes with an i5 4th gen CPU, and 16gb RAM.
You can usually get one for about $300, give or take.
Here's my video on the topic:
I don't know how many instances you could do with your process.
Once you exceed 80% CPU usage, your chances of system crash and reboot are quite high.
So, running multiple instances might not be practical, but it totally depends on how many threads you are running at the same time, and how system intensive that part of SB might be on system resources.

What you need to do is run a single instance test, and make note of how much system resources are utilized.
You might also consider using the premium Automator plugin to try and run a small number of instances in sequence.
However, if any part of your sequence addons fall victim to threadlocks, then the whole sequence will basically freeze.

Depending on your budget, you might consider getting a few machines, and running a couple different sequences at a time.
I would question whether or not all that is even necessary, though. (LoL)
