Ok so I emailed the customer service directly about this.
The reply:
Hi Dave,
WinRed is a PAC, which means we are not directly associated with any campaign, however, our platform was officially endorsed by President Trump!
When you donate through WinRed, your donation goes directly to the campaign you want to support — we make sure it gets there!
You can read more about us here.Please let me know if you have any questions.
Thank you for contacting the WinRed Donor Support Center!
Lillie
The about page helps clarify some. The store it a zero touch stores so the campaigns don't need to manage inventory.
So based on that, it sounds like the store and site is like cafepress: the Trump campaign submits designs like logos and such, and the platform puts it on tshirts, mugs, yard signs, etc... For them while also handling all financial transactions, printing, and inventory management.
But its pretty clear that winred is endorced by any candidate who uses it but the platform itself, being a PAC, was not created by a candidate nor do they have control over it.
Thats how it seems to me at this point.