Most of that looks like really bad chatter to me...

But, if you want help with a Fusion problem, you'll have to post the model, so we can see what toolpaths and settings you used. If you use roughing toolpath for finishing, you can get a pretty awful surface. In correct option settings can also do it. The Fusion CAM is REALLY good, so this is certainly not a limitation of FusionCAM. The 770 should also be able to produce a very good finish, it programmed correctly, though there could be something wrong with your machine.

Regards,
Ray L.