You can ask Steam Support to remove the game from your account so you can try a fresh activation, or contact the third-party seller (like Humble Bundle ) if you bought it there.
Older games often struggle with how Windows 10 and 11 handle the WOW6432Node registry path.
Contact the seller’s support immediately. Most reputable marketplaces have buyer protection programs to issue a refund or a replacement key. 📞 Step 4: Contact Official Support