Move Adobe Acrobat 8 from my old computer

don't 'move' it.

properly install it using the installation files and your serial number.

you can recover your serial number from your old installation, if you can't find it:

windows: http://www.belarc.com/free_download.html

mac:  https://mac-product-key-finder.com/

and

Downloadable installation files available:

• Suites and Programs:  CC 2015 | CC 2014 | CC | CS6 | CS5.5 | CS5 | CS4, CS4 Web Standard | CS3
• Acrobat:  DC, XI, X | X Suite | 9,8 | 9 standard    | 8 standard
• Captivate:  8 | 7 | 6 | 5.5, 5 | 1
• Cold Fusion:  11, 10 | 9.0.2, 9.0.1, 9.0.0, 8.0.1, 8.0.0, 7.0, 6.1, 6.0, 5.0, 4.0
• Contribute:  CS5 | CS4, CS3 | 3,2
• FrameMaker:  12, 11, 10, 9, 8, 7.2
• Lightroom:  6.3|  6| 5.7.1| 5 | 4 | 3
• Photoshop Elements:  14,13,12,11,10 | 9,8,7 win | 8 mac | 7 mac
• Premiere Elements:  14,13,12,11,10| 9, 8, 7 win | 8 mac | 7 mac

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'.