(1) Make sure the website and links you are using are correct.
(2) Follow their instructions for using it according to the demo they allow.
(3) If you like it, fine, if you don't, fine. Nothing lost except some time and maybe something to gain.
This ain't rocket science for goodness sakes! :-)
I am sorry to be not clear enough maybe describing my frustarating experience with the product.
I suppose the demo should be available without prior contacting the sales/support, especially when the site functionality allows registration for new users\prospects.
I saw the link by
Alexey Danilchenko , clicked it, downloaded the demo, installed it (without any prompting to set the user language,. which is OK since English, Russian, German are all good with me). Then I got that purchase\demo window and clicked the Register link, filled out the form and get back to login page without any confimation emails to the specified address. Should I be their tester for free (which partitially I am at my job as a technical writer)?