"Edit in New Studio"
There are some features in Creator Studio that are not fully compatible with Classic Studio. For this reason, if you create content in Creator Studio, you will be able to see it in Classic Studio, but you must switch back to Creator Studio to edit the content that was created in Classic Studio.
Clicking on Edit in New Studio will take you to the Design page for the campaign in Creator Studio.
Editing Classic Studio Campaigns in Creator Studio
You can edit Classic Studio campaigns in Creator Studio. Just click on a Classic Studio campaign to open it in the embedded Classic Studio editor for editing.