Since you can't buy it directly on modern digital stores anymore, here are your best bets for getting it on PC:
Be careful with sites claiming to offer "free downloads" that aren't well-known community hubs like the Internet Archive or Reddit. Many of these sites can bundle unwanted software or malware. Stick to the preservation links used by the Minecraft: Story Mode community to stay safe. Minecraft Story Mode Full Season 2 PC Tutorial Download Since you can't buy it directly on modern
You can still find physical copies for sale on sites like Amazon or eBay. For PC, these are rarer, but a physical disc is the most "official" way to own it now. these are rarer