Credential theft - Adobe Acrobat Reader DC (AcroRd32.exe)

I am working on Cyberark EPM tool. Where in Threat detection part, Endpoint Privilege Management (EPM) montior the endpoint machines for Threat and for other processes.  We can see that Adobe Acrobat file is fetching Windows credentials whenever a PDF file is being opened from a user machine. 

1) Is there any authentication required from user machine everytime when a user opens a PDF file ?

2) Can we consider this as a Threat or Safe ?

Thanks,

Raghav