The security folder is a secure space independent and separate from the outside world.
Follow these instructions to access the security folder on Samsung Galaxy Note 8:
Step 1: Go to the 'Security Folder'.

Access the 'Security Folder'.
Step 2: Choose 'Start'.

Choose 'Start'.
Step 3: Select 'Log in' and log in with your Samsung Account (Refer to how to create a Samsung account here).

Select 'Log in' and log in with your Samsung Account.
Step 4: Set the lock type for the 'Security Folder' app.

Set the lock type for the 'Security Folder' app.
Step 5: Currently creating the security folder.

Currently creating the security folder.
Step 6: The apps available in the 'Security Folder'.

The apps available in the 'Security Folder'.
That concludes the setup process. Wishing you all success.
