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She saw the shabby little cottage but didn't hurry past it.
Literal
[topic-は] shabby small house [object-を] saw-but, hurriedly pass-by-てしまう-not.
おうち is the polite/childlike 'house' (お + うち), softening 家 ('house') — common in storybooks and conversations with or about children. 通り過ぎる is a compound verb: 通る ('pass through') + 過ぎる ('go beyond, exceed'), giving 'pass by, walk past.' ~てしまう adds the nuance of 'do completely / unintentionally / regrettably' — 通り過ぎてしまう = 'pass by [thoughtlessly, completely].' Negation 通り過ぎてしまいませんでした turns this into 'did not [thoughtlessly] pass by' — i.e., she stopped instead of just walking on. The sentence has the cadence of a children's story.