Qrcode not going to correct product returns 404

We are selling a voucher worth a troy ounce of silver.
The purchaser receives the voucher code
If they want to redeem it for currency they have to request it via email then we manually refund them in paypal.
We made a gift certificate with attachserial plugin to allow them to pass it on to a receiver person who then either keep it or redeem it for currency.

I made a attachserial plugin it works except when someone scans the qrcode they receive a 404 page error it should take them directly to either the add to cart page for that product or even better go to my redeem page here
Part of the message is hidden for the guests. Please log in or register to see it.
and type in the code in the "Enter your serial code " field.
This is the plugin url I entered for the qrcode that did not work

Part of the message is hidden for the guests. Please log in or register to see it.

Should I instead enter the actual url for the add to cart button for that product
Part of the message is hidden for the guests. Please log in or register to see it.


This is the plugin url in Joomla

Part of the message is hidden for the guests. Please log in or register to see it.


I am trying to allow them the buyer to send or give out the coupon and the person could scan the qrcode on their phone and then redeem it.
The steps I have so far are:
1. buyer sends email to a person they want to redeem the coupon
2. The recipient of email prints and scans coupon qrcode with their mobile phone app
3. It should then send them to the site and they then should be able to redeem
However at this point they must register then go to my redeem page
Part of the message is hidden for the guests. Please log in or register to see it.
and type in the code in the "Enter your serial code " field.

Q1. Is there any way to enter an url in the attachserial plugin to:
a. have Hikaserial send them to my paypal account and have them receive a refund?
b. go directly to the redeem page
Part of the message is hidden for the guests. Please log in or register to see it.
and type in the code in the "Enter your serial code " field. Then be automatically registered and receive the emails
c. or at least go to the registration page and then to the redeem field
Part of the message is hidden for the guests. Please log in or register to see it.
and type in the code in the "Enter your serial code " field.

Q2: The next question I have is after the buyer gives the qrcode or the serial code to another person(similar to a gift certificate or Eticket) scenario the receiver has to:
a. go to my website pick the matching product (if they dont pick the matching product they get an error message
Notice
The coupon you entered cannot be used for the products in your cart)

In order to redeem the purchase how do I set it up with one of these options?
I. email shows product and add to cart product link for that product ?
II. have the error message show the correct product and add to cart product link for that product ?
III. in language editor say pick a different product and add to cart product link for that product ?

b. add to cart
c. register then go to the redeem page
d. if they want to exchange it for cash or refund then they have to email me and request it then I have to manually send a refund in Paypal.


if you want the sign in to my Joomla I will provide it with th ehide code in my reply?

Lets take it one step and question at a time. I will create new topics for each of my other questions.

Is there any way to enter an url in the attachserial plugin in the qr code dynamic field as shown in the screencap below?
gyazo.com/89534c68ff17e21b3b38512335bc33c7
In other words can I enter an absolute url like below ?

Part of the message is hidden for the guests. Please log in or register to see it.