Since installing norton 360 on my iphone I am unable to use check out when purchasing something thru the Sam's Club app..

Which iPhone and iOS version are you using?

Are you using Wifi or Cell data for your connection when you get blocked?

There are two things that might be involved here. Norton's Web Protection feature under the  Internet Security section might be blocking your access. When active, this feature will display a VPN icon in the iOS notification area at the top of the screen. This feature has been known to cause connection issues. Next time you get blocked while checking out, try turning Web Protection off and see if that helps.

If that does not help, be sure that you have the VPN feature off in your 360 app under the VPN section. Many web sites do not allow access from known VPN IP addresses. They do this for copyright, legal, and political reasons. There is nothing a VPN provider can or should do to circumvent these legal protections.