맞추다 is fitting things together so they agree, and the clause in front gives how. In these lines that is calling ahead to coordinate outfits, talking it over and finding a middle ground as a couple, adjusting a setting a bit further, comparing answers with others after an exam, and accommodating someone's personality. Keep it apart from 맞히다, which is getting an answer right or hitting a target; the two sound close and are constantly confused.