This link will work until you tell me you have the CAB file, or until tomorrow morning, whichever comes first:
Acrobat CAB file for ARM Pocket PC
I have uploaded this uncompressed, as you have not stated whether or not you have a ZIP or RAR client installed. So instead of being a 2.5MB ZIP file it's almost 5MB. Hope you have a good connection. If you get raw code, as often happens when trying to download CAB files in Pocket IE (it's a server MIME configuration problem sometimes), then I suggest downloading the standalone EXE for EZDownloader, a small freeware download manager. Just copy the address for this file, then open EZ, and it'll be already there in the address bar. Just tap Start do download.
http://masataka.mailbbs.com/ez/en/
If you need to intall to SD or CF card, then get another standalone EXE called CabInstl, here:
http://s-k.al.ru/wincepdaru.html
Hm. It seems EZDownload is in a ZIP file. You'll need something to unpack that, if you don't have yet. TotalCommanderCE is free... but is distributed in a ZIP labelled/packaged as an EXE. So here's the ARM version of that CAB for you too:
TotalCommanderCE