Snapchat doesn't directly enable you to screenshot a Snap story in the normal way. The reason for this is that Snap stories are often meant to be ephemeral and private to some extent. If screenshots were freely allowed, it would go against the nature of the feature which is about sharing quick, temporary moments without the worry of the content being permanently saved through screenshots by others.
Well, generally, Snapchat is designed to not allow easy screenshotting of Snap stories. However, there are some unauthorized third - party apps that claim to be able to do it, but using such apps violates Snapchat's terms of service and can also pose security risks to your device and your Snapchat account. It's not a recommended practice.
No, Snapchat has privacy settings that prevent screenshots of Snap stories in most cases. This is to protect the privacy of the users who post the stories.