Please use below code in theme function.php file to set auto paid referral status.

if (!function_exists('can_receive_woo_wallet_credit')) {

    function can_receive_woo_wallet_credit($affiliate_id) {
        $ret = false;
        // Get global setting.
        $global_woo_wallet_credit_enabled = affiliate_wp()->settings->get('woo-wallet-all-affiliates');

        if ($global_woo_wallet_credit_enabled) {
            $ret = true;
        } else {
            $ret = affwp_get_affiliate_meta($affiliate_id, 'woo_wallet_credit_enabled', true);
        }
        return $ret;
    }

}

if (!function_exists('AffiliateWP_Woo_Wallet_Autopay')) {

    function AffiliateWP_Woo_Wallet_Autopay() {
        if (!current_user_can('manage_payouts')) {
            return;
        }
        $new_get_affiliate = new Affiliate_WP_Referrals_DB;
        $array_aff = $new_get_affiliate->get_referrals(
                array(
                    'number' => -1,
                    'offset' => 0,
                    'referrals_id' => 0,
                    'affiliate_id' => 0,
                    'reference' => '',
                    'context' => '',
                    'status' => '',
                    'orderby' => 'referral_id',
                    'order' => 'DESC',
                    'search' => false
        ));
        foreach ($array_aff as $aff) {
            if (can_receive_woo_wallet_credit($aff->affiliate_id)) {
                $ref = $aff->referral_id;
                $ref_status = $aff->status;
                if ($ref_status == "unpaid") {
                    affwp_set_referral_status($ref, "paid");
                }
            }
        }
    }

}
add_action('init', 'AffiliateWP_Woo_Wallet_Autopay');