Group codes so a report can answer one question
A campaign is the piece of work; tags cut across campaigns; folders keep the lists navigable. Three different jobs, deliberately not the same feature.
Campaigns
One campaign, many codes and links. Reports can treat it as a single subject when you want the total, and as its members when you want to know which placement worked. Short links can join a campaign as well as codes, so a print run and the email that followed it are one story.
Tags
A code can carry several. Useful for the cuts that do not respect campaign boundaries — a region, a quarter, a product line — and they are a filter dimension in every report.
Folders
For finding things rather than reporting on them, on codes, links, cards, pages, forms and GS1 links alike. An item lives in one folder or none, which is what keeps the rail honest: anything unfiled is visibly unfiled rather than quietly hidden.