I have purchased the license to this file.
My client would like very minor adjustments to the graphic design.
I would like the contact information for the designer to request possible changes.
How do I reach out to the contributor?
I think your expectations are too high. This is a Stock/Royalty-Free Image library, not a custom design studio.
[Moderator moved from Stock Contributors to Stock.]
Most Stock vector files (AI/EPS) can be changed with Adobe Illustrator or InkScape. Are you familiar with either of those applications?
Adobe do not provide any personal details of contributors, nor will they contact a contributor for you. However, contributors do have a name shown. Often this is a business name and you can Google for it. You will see if you find contact details of the artist or their studio. (I did read that stock photographers can have a profile page, but I can't find a way to view it!)
Finding the Stock contributor is no guarantee they're available anymore or that they'd be willing to drop everything and make changes to artwork they received 20 cents for. That's just not realistic.
Stock art is stock art, not custom art.