Thank you for posting your query here. First, try to download your document. Then open it with the Adobe Acrobat Reader mobile application. In the application choose the 'Files' option from the bottom panel. Then browse the downloaded document. You can then save the document in the device or document cloud using three dots on the top right corner.
Files opened with the Acrobat Reader mobile app are automatically saved to your local device. To easily access them from all your devices, simply save your document to Adobe Document Cloud by signing in or creating a free Document Cloud account.
For further reference: FAQ | Adobe Acrobat Reader mobile app