What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Unfortunately, you cannot use our form as way to have a Login page or login form.
Every time you use elements on the form that resembles it as login page or form (i.e. login name, password, email account/password combo, account name/password combo, username/password ) the Anti-Phishing system in place will immediately suspect it as a phishing form, and will suspend the form/s and the account.
We actually have a new feature called Form Encryption. You can check more details here
You can protect/secure your forms with encryption.
I suggest checking this user guide also.
The method described on the user guide might also help on what you need.