How can I create a field with multiple choice + a text area?

Hi, I'm trying to create an area where customers can choose multiple sized bags and then type in the quantity required next to each size. i.e.

                    SIZE                                  QUANTITY

(tick button), Mini W125 x 150 x 100mm (field to type quantity)

(tick button), Small W125 x 150 x 100mm (field to type quantity)

(tick button), Medium W125 x 150 x 100mm (field to type quantity)

(tick button), Large W125 x 150 x 100mm (field to type quantity)

I have tried using the configurable list and multiple text fields widgets but neither seem to be configurable in this format. Please help! 

The field from the screenshot you provide is the Configurable List widget. However, I would not recommend this widget for what you are trying to achieve because you would have to add all options in a single row, and you will not be able to perform a calculation if you need it. 

I would suggest you to use a payment field. 

Setting Up Your First Order Form

How to Add Options to Payment Forms

If you want to create a payment form without payment vendor integration, you can use the Purchase Order payment field.

How to Create Payment Form with Purchase Order