Eliminating Prompts when opening PDFs from SharePoint using MacroView

Prompt 1: Some files can harm your computer.

If you receive the above message when opening a PDF file, the prompt can be suppressed by setting the setting below in the registry to 1

Computer\HKEY_CURRENT_USER\Software\MacroView\DMF\UserOptions\OpenFilesDirectFromUNCPath 

Prompt 2: Check Out & Open, Open, Cancel

This is displayed by Adobe as part of its improved awareness of SharePoint.  Various internet articles note that this prompt is displayed even if the user has read-only access.

To disable this message you must disable SharePoint Integration in Adobe using the following steps:

1. Open the registry editor.

2. Go to HKLM\SOFTWARE\Policies\Adobe\<product name>\<version>\FeatureLockDown.

3. Create a key called cSharePoint.

4. Create a DWORD value called bDisableSharePointFeatures.

5. Set its value to 1.

Note: You should also consider disabling the Adobe SharePoint Integration if you use special characters in PDF file names or the SharePoint folders in which they reside. Special characters such as '#' and '%' are supported by SharePoint Online and SharePoint Server 2019 in file and folder names but the Adobe SharePoint Integration uses a SharePoint API that is not special character-aware. If the integration is not disabled it will result in errors and unexpected behavior within Adobe when handling files whose paths contain special characters.

https://www.adobe.com/devnet-docs/acrobatetk/tools/AdminGuide/sharepoint.html#disabling-sharepoint-integration

More Adobe articles:

Disable protected mode message in Adobe Reader DC

SharePoint, Office, Windows and Adobe version support