This is due to their SSL certificates already expired (on August 29, 2020), and thus modern browsers reject to load the resources (particularly for
static.cognitoforms.com domain) that the page needs to work for being unsecured.
The real fix has to be done from the Cognito Forms' side to renew the SSL certificates (which is out-of-scope for end-users).
The workaround is to allow the browser to load them (tested on Chrome):
- Open one of the resources under
static.cognitoforms.com domain (e.g. https://static.cognitoforms.com/app/npm.core-js.d28959b695025102af27.js)
- Chrome will show "Your connection is not private" warning
- Click the "Advanced" button on the bottom
- Click the "Proceed to static.cognitoforms.com (unsafe)" link
- Reload the login page
Note that browsing HTTPS websites with invalid SSL certificates in general is insecure since the connection is not actually secured. Use with extreme caution!