My tank has been up for about a month and was wondering what these macro algae are and if they're bad?

The first one is red in color and there are few clumps growing around the tank on different pieces of liverock

The second type is green and is only growing on one piece.

Any ideas?

The second is a Caulerpa species and I think an invasive one. IMO, you should carefully try to remove it without breaking it.

What kind of problems will I have if I leave it?

caulpera has a tendency to overgrow tanks pretty quickly. you don't have to remove it, but later it will be much harder to do so.