How can I most effectively use the new ad manager with a limited budget?

I’m trying to advertise a small project I’ve been working on. However, I remembered that roblox replaced the old sponsored ad system with the new ad manager, which is a lot more confusing.

Let’s say I have 10k robux to use for advertising.
Is buying ad credits to set up a “campaign” even worth it? I’m a little skeptical as to whether buying irreversible ad credit is worth it.

That being said, how exactly do ad campaigns work and are they more or less effective than the original sponored ad system?