We also suggest using cryptpad (flagship instance is https://cryptpad.fr/). To make a form which people can fill out. Cryptpad has zero knowledge encryption meaning those who own/run the server cannot see the data. It would probably be a better solution than asking people to reach out personally.
A note, when sharing any document make sure you use the share button and not the URL as the URL is admin access, plus the share button allows you to control access further. Also, we suggest signing up (at least for the form maker) as otherwise all the information will be gone after a few days.
A personal note: We love it because it requires no email address etc to sign up, just a username.