Tracking conversion rates in an unbounce form with an iframe'd GiftUp store

Question

I have an Unbounce page which hosts a GiftUp gift card iframe to buy a gift card. I need to track conversion rate.

With the iframe'd store, GiftUp, I cannot set a redirect to another Unbounce page to capture the conversion once a purchase is made.

With the GiftUp js, I do not know how to have the unbounce host capture the conversion.

I understand I am new in this and I will improve my question with your recommendations.

I am looking for advice.

Thank you,

References:

GiftUp Conversion tracking via JavaScript https://help.giftup.com/article/136-conversion-tracking-via-javascript

External Conversion Tracking with Unbounce https://documentation.unbounce.com/hc/en-us/articles/19956511113876-External-Conversion-Tracking-with-Unbounce

I do not have a path to try anything since no approach looks to do what is required.