Assuming you have a good internet connection then try closing down the app in your multi tasking and then soft reboot the phone by turning it Off and On.
Then try launching it again.
If no joy then go into settings then apps and scroll to the Samsung Members App.
Go to storage and clear cache and cookies and then try launching.
I have an issue with Samsung Members app. I recently got a Galaxy S9 and when I start the Members app I can press next on the initial set up. I am then greeted with the message:
'Your service country may change along with related content in the Samsung Members app. This will overwrite previous information'.
After tapping OK I then get the error message:
'Server response error
Server error. Try again later. Status : 400 Error : 4047 Message : Samsung Members Authentication is required'
I have tried to launch the app when connected to wifi and 4G but get the same error. I have tried clearing Cache and Data and even uninstalling and reinstalling the app but I can not get it to work.
Any help would be greatly appreciated.