Installing AND getting it to work on second machine

Before anyone gives the answer of 'you can install on second machine' or 'you can install on as many machines as you want'.... but can only use one at a time (and it has been said you can remain signed in on both machines) the question is, how do you get Adobe Acrobat DC to work on the second machine.  The tools only say (add) and do not allow them to be used, and the options are 'start a free trial' or 'purchase'.  I purchased and simply want it on my main computer that was not available when I purchased and originally downloaded.

How do I get it to work on the second machine.