accessing Google Calendar

I am a 77-year old novice struggling with what many consider day-to-day normal tasks.

I have successfully installed Google Calendar on my Galaxy S8 tablet. An icon on the home screen allows me to access the calendar direct.
I have tried to install the calendar on my Galaxy S5 phone, but the (different) icon produced opens another window, with what appears to be the correct calendar icon and a message telling me it's installed. The calendar icon however doesn't open anything, and nowhere amongst the apps or home screens is any shortcut to give access to my Google Calendar.

Any assistance greatly appreciated.