Hey Nico,
I am sorry but we will not allow password protected views via iframe. We cannot weaken the CSRF checks because this will lower the security of cloud.seatable.io in general.
If you want to keep the password protection, then create an preview-image and link it to the correct url. Or if you don’t want to send the user to cloud.seatable.io then you have to protect your view with another kind of protection like HTTP-Basis Authentification in your webserver or add some code like php or python pending of your website language.
Here is a short link how to use http basic authentication in nginx: Restricting Access with HTTP Basic Authentication | NGINX Documentation.
If you have apache use this manual:
Authentication and Authorization - Apache HTTP Server Version 2.4
Best regards
Christoph
