I have no idea how to actually do this

Go to "Games" and under "Collections" click on "Treasure maps!"

It says I have 0/9 but they are in in my invantory!

Are you on the Original map page, or the Omen Islands one? It shows the original one first, you need to click on Omen Islands (at the top) to go to the other one. Or here directly

thank you that worked