Unfortunately only Adobe Acrobat Pro or Adobe Reader and Bluebeam Revu are supported for Open and Edit pdf files in ShareFile Desktop App. Do you intend to support other pdf file editors in the future? Not everyone uses Adobe Acrobat.
Thank you for your feedback. The primary reason we currently only support these applications is due to the efforts involved in testing and verifying proper compatibility with the Desktop App and our Open/Edit functionality. Various applications have differences in how they modify and save the files, so in order to ensure data integrity and reliability we limit the functionality to those specific applications that are within the scope of our testing. If there is a specific application that you utilize (I believe from another thread there was reference of PDF-XChange), please let us know, and based on customer demand and resourcing we may be able to conduct testing and add additional applications to our supported list.
As an alternative/workaround, you should be able to continue downloading the files and editing locally, then re-uploading (though I understand this is not ideal from a workflow perspective).