when I tried to download ArcGIS Desktop it prompts:
Our records indicate that this account is not eligible to access the ArcGIS Trial Downloads. Visit arcgis.com and sign up for the ArcGIS Trial or, if you need assistance, contact firstname.lastname@example.org.
Have you already used this account for a trial?
I have registered this account for trial but not yet started using the account as i am not able to download software.
I am not 100% sure so I cannot say if the trial starts from when you register or when you authorize.
So, first of all check the email that has been sent and look at the date, maybe Jayanta is right. ("The object should be: Esri - Your free ArcGIS trial")
Then, if the date it's ok, be sure that the account you are logged in is the correct one. It can happen that you mix up if you have more than one.
For educational license, please contact your local Esri distributor.
For trial license, ensure that the trial period hasn't expired.
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