Outlook Calendar & Google Calendar

I cannot see my Outlook Calendar on my iPhone calendar or on the ios Outlook app. It just keeps showing me my google calendar. I keep looking up ways to fix it but I can't find anything specific for THIS problem. 

I think part of the problem might be I used the same Gmail address for both accounts, Outlook and Google. Is that the problem? Then why when I login to Outlook on my windows computer I can see my Outlook calendar, but when I use the app on my iPhone it only allows me to see my google account calendars? 

IM CONFUSED AND NOT TECH SAVY ENOUGH TO FIGURE IT OUT.