If you are on a Windows computer, see Install an older version of Adobe Reader | Windows.
Installing Adobe Reader is a two-step process. First you download the installation package, and then you install Adobe Reader from that package file.
Before you install, make sure that your system meets the minimum system requirements.
To see if other users are experiencing similar download and installation problems, visit the Acrobat Reader forum, or the Deployment & Installation forum on AcrobatUsers.com. Try posting your problem on the forums for interactive troubleshooting. When posting on forums, include your operating system and product version number.