Adobe Acrobat Pro DC 2015 is a very old, unsupported version . Adobe no longer provides security updates or patches for it. Using it poses serious security risks (e.g., opening a malicious PDF could compromise your system).
Open the mounted volume and double-click the installer bundle. adobe acrobat pro dc 2015 update download
A focused feature page that helps users find, verify, and safely download official updates for Adobe Acrobat Pro DC 2015 (maintenance releases and security patches), plus guidance on installation and verification. Adobe Acrobat Pro DC 2015 is a very old, unsupported version