can't get birthday field to fill

I can't figure out how to get birthday field to fill on https://hp2win.com/monster-brewing-company-colorado-snowmobile-sweepstakes-beast2025-03312025/

I have tried inspecting the page and I added these fields to my login:
Text Field mm set as 01
Text Field dd set as 15
Text Field yyyy set as 1970
this did not work

I tried adding Date field called Birthday set as 01/15/1970
this did not work

Can anyone teach me how to fix my login for this site to fill my birthday?

Thanks,
Tobey