I'm not able to share a link with 'can edit' permissions

I don't have the desktop app installed on this computer, so I cannot show that right now.

In browser:

... and if I clink on Link settings, I get:

... so it looks as if the advertisement that we can do Can Edit with Basic is untrue.

This doesn't really have to do with your specific plan, Kurt. 

Is this folder inside an already shared folder perhaps?

And are you the owner of that parent folder?

Is this folder inside an already shared folder perhaps?

-> How can I tell that?

And are you the owner of that parent folder?

-> How can I tell that?

Does the parent folder of the folder you're trying to share, have a "two people" icon on it instead of a plain blue folder? 

That would indicate the the parent folder is a shared folder.

And to check if you're the owner of the parent folder, click on the "Share" button next to it in your "All files" page and then click on "who can access".

Folder App in Dropbox has plain blue folder.

Folder Yodeck Digital Signage in App has a "puzzle piece" icon on it instead of a plain blue folder.

Folder Sally in Yodeck Digital Signage has plain blue folder.

Folder Amy in Sally has plain blue folder.

They all have a "Share" button next to it except for the one with the "puzzle piece" icon.

No matter above or below the "puzzle piece" icon in the folder structure, when I try to Share they all say only Can View can be used, but I should upgrade to enable all Link Settings.

Who can access is Only you for all of them.

Hi kurtbaud, the puzzle piece means it's part of an API connecting to a specific app (most likely Yodeck). 

Due to this, you can't share the App or Yodeck folder, or any subfolders, to any user since only the app in question can access that entire folder structure.