These are all different things, so let's explain and then solve:
MaxCDN is a CDN service provider.
DreamPress is a WordPress hosting platform.
W3TC is (primarily) a caching plugin.
As you can see, these are all different. Fortunately, you can use all of them!
You can install W3TC in your DreamPress-hosted WordPress site, and configure it to be used with MaxCDN.