If you have a Mac without a DVD drive, you must create a USB installer. You will need access to a Mac that has an optical drive (or an external drive) to read the disc image.
Apple provides a hidden support page: This page gives instructions for customers who previously purchased Snow Leopard through the Mac App Store (available from 10.6.6 onward). If you have an Apple ID that was used to download Snow Leopard before, you can find it in your Purchased tab of the App Store (if using a compatible older Mac running High Sierra or earlier). os snow leopard download
As of 2026, Apple no longer sells Snow Leopard DVDs directly. However, you may find new-old-stock on eBay or other marketplaces. The part number is (10.6.3 retail DVD). Avoid burned copies or random ISOs from torrent sites—they may contain malware or be corrupted. If you have a Mac without a DVD