Save data from repeating group using external button

Problem 1: Saving Data from repeating group using an external button
Problem 2: Best way to save this data

So I have this form I build, where people fill out the rubbish they want removed.

I want them to be able to put in the rubbish type, then allocate a rough amount to that type, which I have visually working as seen below, using a multi-dropdown and RG

I am struggling to find a way to extract the data from the RG and place it into the data base. I have an “Order” thing and a “Rubbish Type” thing, the first is the where I want to save all the data from this form and the second is the rubbish options shown in the drop down.

My thinking is that if/when I can get this data from the RG I can just save it as a list of “Rubbish” things, as they could have multiple rubbish types, and that way I can easily print out all the information later.

Any help would be great. Cheers