Where will The user data be saved and can users login in my website if I use JotForm?

Is there a database system in JotForm where user information are stored and can I access them through here? Also, can users login through here? If not, what additional steps do I have to take? Thank you.

Yes, submissions data is stored on your JotForm account and it can be accessed following this guide: https://www.jotform.com/help/269-How-to-View-Form-Submissions 

Now, it's not possible to ask for login info on JotForm forms since it goes against our terms, if your purpose is to share the submissions data and protect it using a password then you may just share the submissions page as explained on this guide: https://www.jotform.com/help/199-How-to-Share-Form-s-Submissions-Page 

You may create reports to share submissions data: https://www.jotform.com/help/326-How-to-Create-Form-Reports-in-JotForm 

Or you may also set up sub users to share forms and submissions data, they have their own account where you will be sharing the needed information, please find more details about it here: https://www.jotform.com/help/232-How-to-Share-Forms-with-a-Sub-Account-User 

If you have more questions, please let us know.