Just asking 2 questions:
1. Can I install the InDesign free trial in two different computers? (the same adobe account, in the time limit of 30 days)
2.How can I open the file that is made by CS5 or previously(back to CS2) on CC or CS6?
As far as I know there is no problem with installing the trial on two machines. If you do have trouble, just create a new Adobe ID and install under that.
To open old files, use File > Open...
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