do i need to use the akamai download manager for acrobat pro xi?

no.

even when akamai is offered for download, you can always cancel and download directly from adobe.com.  in addition, prodesigntools.com offers (almost) all the adobe programs via direct link.

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:  9 | 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:  6.4|  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'.