This short article is to resolve the myth of creating attachment column in Office 365 SharePoint.
In actual fact, you do not need to create a column. What you need to do is enable or disable the attachment for the SharePoint List.
To ensure the attachment do the follow.
1. Click List Settings in your List ribbon.
2. Click Advance Settings.
3. Ensure Attachments to list items are: Enable.
You can then Attach file for your list item.