If the HTML form submitters need to authenticate there are some considerations:
Form users would need an Integrify account if you want to send them to follow on tasks etc. If this is the case you will need to provision users. You could send them through our SAML proxy which auto-creates users. You could code your form to check for a cookie and if it is not there you would send the person through the SAML proxy which would then send them back to the form. This assuming you create a form outside of Integrify and use the API.
If you would prefer to use the widget API you may be able to use the SAML proxy depending on your SAML Identity provider and policies. ADFS for example will not allow access from the IFRAME that renders the widget by default.
We would recommend you create your HTML form and contact us to consult with you regarding the API. You may also need services if you'd prefer for us to set up the SAML proxy.