Portal accounts and logins for external users?

There are two ways to achieve this

1. Once the external user has requested a quote >> Write it to record >> Display the unique identifier of the record to user as a reference id. Give the user a page in portal where they can enter the reference id and view or act on the record.

2. Ask for details like name, email etc., from the user while requesting a quote. With those details create user inside appian using createUser smart service and add them to required groups. Once done an email will be sent to user with Appian login credentials. With the login details, the user will be able to login to Appian site and look for the details regarding the quote.

Is it also possible to make a login page in my portal? When the anonymous user enters their email and password, can I redirect them to the appropriate site in Appian?

Yeah, just have an interface with some text fields to collect email id and name and other stuffs. Have a button called Register, upon clicking which you have to call a process using a!startProcess() that have create user and adding to group logics. Once done, the user will get the login credentials in email.

Got it. What you've talked about is a sign up or register page in the portal.

My question was whether I can have a custom sign in or login page in my portal. Once the user registers with his email/password in the register page, can they use the same info in my custom login page to enter into my Appian site? How will the redirection on succesfull login happen?

Portal users are not Appian users until they have an account created inside Appian. You have to build a process to create the user inside appian based on email provided in your portal's registration page. 

Only after that he will be able to login to Appian

Understood. But once the user is created, we can have a custom login page in our portal where the user can enter their credentials and be redirected to appian site? is this possible?

Otherwise from where will the external user login to their appian account other than from the email link?

How can we handle this redirection from the custom login page to the appian account of the user or the appian site?

Understood. But once the user is created, we can have a custom login page in our portal where the user can enter their credentials and be redirected to appian site? is this possible?

Otherwise from where will the external user login to their appian account other than from the email link?

How can we handle this redirection from the custom login page to the appian account of the user or the appian site?

Once user is created, Appian sites should be used as primary source of information not portal

You cannot build your own custom login page. Not in a portal and not in a site or any other Appian UI.