Just type in "none" for company, i don't see why they would not let you into a webinar because if that
I do it a lot on annoying forms that i don't want to fill in the first place. Like some places that give you a form before they let you download something. In those cases my name is "none" my last name is "none" my address is "none", my phone number is "000000000" and sometimes even my email is "none@none.com". Just enough to get past the automated check that i filled everything and the website gives me the link i wanted.
Tho for things like this i would fill out at least the basic stuff like my name.