A green carpet wouldn't harmonize with this blue curtain.
Literal
Green [of-の] carpet [with-では] this blue curtain [with-と] won't-harmonize [probably-だろう].
調和する ('to harmonize, be in harmony') takes と for what it harmonizes with. しない ('does not do') + だろう ('probably') — hypothetical prediction about color matching. Interior-design register.