How to allow users to create their own collection based on existing database?

[lunarity]

Hello!
We are a brand that creates limited edition pins. I have been logging our pins into a google spreadsheet (features image, pin name, LE, variant, artist, type of metal, drop date, and drop price). 

I would like to allow users to create their own collection within the app; they would do this by selecting an existing pin (they cannot modify the details we put in) and they would click 'add to collection' button. At the bottom of the app, I would like for there to be a 'My Collection' tab.

I believe I have to create a separate spreadsheet with a column for users, but I'm not sure where to go from there or how to link everything. I am including screenshots to help clarify what our database looks like! Thank you

Home page is simple, shows each pin (name and limited edition amount)

When a pin is clicked from home page, it shows all the info for that particular pin.

I'm not sure how to get rid of the edit button, that won't be enabled in the end product. Maybe can change it to a + button to add to collection? 'My Collection' tab would ideally pop up next to Lunarity Pinfo on the bottom menu.

Thank you for your help!!