My platform is Nintex Form and Workflow for SharePoint 2019 and I am developing a task form to allow UAT tester to upload their UAT result attachment to Workflow task form (via Flexi-task). And I have added a particular workflow in the those workflow task list to copy the UAT result attachments to Document Library under specific folder, then the core workflow will build the HTML table with hyperlinks to access the UAT attachments stored in Document Library. 

My question is how Nintex Workflow for SharePoint to get all attachment links under specific folder of Document Library?

I have tried to get the attachment links via GetAttachmentCollection() method of Lists web service _vti_bin/Lists.asmx but in vain. It seems lists.asmx is only for SharePoint lits but not for Document Library.

Thanks a lot.