downloaded photoshop elements 12 in 2 formats, dmg and 7z. I could not open either. Where is the download manager?

if you have mac, install the dmg and trash the 7z.

if you have win, you need to download the matching exe, put both the exe and 7z in the same directory and then double click the exe.

Downloadable installation files available:

• Suites and Programs:  CC 2014 | CC | CS6 | CS5.5 | CS5 | CS4, CS4 Web Standard | CS3
• Acrobat:  XI, X | 9,8 | 9 standard
• Premiere Elements:  13 | 12 | 11, 10 | 9, 8, 7 win | 8 mac | 7 mac
• Photoshop Elements:  13 |12 | 11, 10 | 9,8,7 win | 8 mac | 7 mac
• Lightroom:  6| 5.7.1| 5 | 4 | 3
• Captivate:  8 | 7 | 6 | 5.5, 5 | 1
• Contribute:  CS5 | CS4, CS3 | 3,2
• FrameMaker:  12, 11, 10, 9, 8, 7.2

Download and installation help for Adobe links

Download and installation help for Prodesigntools links are listed on most linked pages.  They are critical; especially steps 1, 2 and 3.  If you click a link that does not have those steps listed, open a second window using the Lightroom 3 link to see those 'Important Instructions'.