Multi page forms with save and continue function

In the new multi-step forms, how do we achieve a save and continue function?

In order to achieve that functionality please go to Settings and locate the Continue Forms Later option.

You need to Enable that option and select Save & Continue Later. After you enable that on your form it will appear another button that says Save & continue later.

When you click on that button the user can write down the email address and an URL will be provided through the email.

I hope this is helpful. Please feel free to ask if you have any other question. 

As mentioned by @lumiardian, you may enable the Save & Continue Later option from the Form settings. Please see the screenshot below:

Once the option is enabled, the form shall be displaying the Save icon as shown below:

Hope this information helps!