What is meant by “Energy is exactly conserved locally in GR. Inflation and Dark Energy isn't an exception to this.”?

In a matter dominated Universe on scales much smaller than the Hubble length ($approx 4$ Gpc), and not near dense collapsed objects like neutron stars and black holes, the standard assumption is that one can use Newtonian physics and so energy is conserved on those small scales. One can also accommodate a cosmological constant by adding a repulsive force which increases with distance. As this can be accomplished by a potential proportional to distance squared you can still have energy conservation by exchanging kinetic and potential energy.