Things like sending the appropiate email, creating a referral page have been configured in advance. You just have to enable the REFERRAL_INVITE email inside the email.config.ts file. Here’s how it works: If a user is on the app/refer page and submits the form - the following email will be sent to his friend: 
await axios.post(postUrl, {
    to: values.email,
    subject: `You've been invited to join ${appConfig.company.name}!`,
    emailType: EmailType.REFERRAL_INVITE,
    variables: {
        nameOfReferrer: dbUser?.email,
        referralCode: dbUser?.referral_code,
    },
});
Then, when his friends clicks the link in the email he will redirected to the auth/sign-up page which includes the referralCode in the URL like so */2mrw.dev/auth/sign-up/mode=magic-link:ref=5ZHA81. If his friend now signs up with the referral code our processReferralSignup fn will be called where we can add some custom code to decide what the friend / or both users should get for a successful referral:
This boilerplate doesn’t come with rewards out of the box. You’ll have to create the custom logic for it as referral rewards are quite different for each app.For instance, for Reelify, I’ve decided to give both users video credits to create more videos. However, for another app that could be giving one month for free.
export const processReferralSignup = async ({
    newUserId,
    newUserEmail,
    referralCode,
}: ProcessReferralSignupParams) => {
    const { data: existingReferral } = await getExistingReferral(newUserEmail); // check for pending referral (email, password, magic link flow, etc.)

    if (existingReferral) {
        return await updateReferralToCompleted(existingReferral.id, newUserId);
    }

    if (referralCode) {
        const supabase = await createClient(); // if no pending referral but we have a referral code (Google auth flow)

        const { referrer } = await getReferrerByReferralCode(referralCode);

        if (!referrer) {
            return { success: false, error: "The referral code is invalid" };
        }

        const { error: insertError } = await supabase.from("referrals").insert({
            referrer_user_id: referrer.id,
            referred_email: newUserEmail,
            referred_user_id: newUserId,
            status: ReferralStatus.COMPLETED,
        });

        return { success: !insertError, insertError };
    }

    /**
     * FYI: This is the part where you can add new logic to the referral flow such as adding credits to the referrer and the referred users accounts, etc.
     */

    return { success: true };
};