[grok2]

You really should simply try it out (A/B testing) and see what happens...your own data will help you decide.

1) Initially don't require the contact form for some time 2) Then, require contact form for some time 3) Finally, try having an optional contact form -- they can still download the trial even without filling out the form.

One of the reasons to try this out instead of relying out info from others is that the behavior may be specific to the kind of software you are selling and specific to the target niche and so generic advice won't be suitable.