There are no legal downloads of System 7.1, whatever anyone thinks about the whole software resriction process. It was the first of Apple's Reference Releases, which had, and still have, to be bought even years after their release. This will fill you in. You will note that the Calgary link on that page does not work, and ditto for all other download sources known to Apple.

All is not doom and gloom, however, as 7.1, in particular, turns up quite frequently in new and near-new condition (on floppies) in eBay, but much less frequently on CD.

de

And then there is this: http://lowendmac.com/deals/best-classic-mac-os-prices.html