When i click on "try", it gives me a page but with no download button. All it says is this as below:
To download trial versions of Creative Suite software, you need to install the Adobe Download Assistant. After installation, the Adobe Download Assistant will start your product download automatically.
How do i download this download assistant?
(Is this happening because i have adobe creative suite CS4 on my computer?)
Having CS4 on your computer will not affect the download of the Trial, try this link to get the download of the Trial version of InDesign CS5.5, which is the latest version.
It's possible you have some security settings in your browser that are preventing the script that shows the button from running.