I want to send PDFs to clients for them to sign on the mobile Adobe Fill & Sign App. However, rather than opening the PDF in the mobile app through their email, I would like them to be able to use the option within the Fill & Sign app to use a "Web URL." In other words, I want our clients to be able to open the Fill & Sign App on their phones, click "select a form to fill out," select the "Web URL" option, and use a URL which we have provided for them to access the PDF they need to sign.
However, it is unclear which URL types are supported through this feature. I have tried to link to PDFs hosted on a number of different servers, including my company's server, DropBox, and Google Drive. None of the URLs work, and when I paste the link and press "fill form," I either get an error message saying "Could Not Import Document" or "This form could not be opened because the link is not of a supported format."
Adobe's instructions and the FAQ for the mobile Fill & Sign app are very limited, and do not address the "Web URL" option. I would appreciate any guidance on how to make a document and its URL compatible with this feature, and to better understand what is causing the error messages that I'm getting in the app.