Why is a PIN code required to open the app?

The PIN code is to block unwarranted trespassers when your phone is unlocked. When one enters the code incorrectly 3 times, the app will be blocked for 3 minutes. 3 more incorrect PIN entries will get the app blocked for 15 minutes. You can always enter the app directly during these blockages with your fingerprint, but do your best to remember the PIN code you created.