Mark Rybarczyk

Little late to the party here but if you add localhost:3000 to CORS in your bucket it should work. example in S3:
[
{
"AllowedHeaders": [
"Authorization"
],
"AllowedMethods": [
"GET"
],
"AllowedOrigins": [
""
],
"ExposeHeaders": [],
"MaxAgeSeconds": 3000
},
{
"AllowedHeaders": [
""
],
"AllowedMethods": [
"GET",
"POST",
"PUT"
],
"AllowedOrigins": [
"https://localhost:3000"
],
"ExposeHeaders": [],
"MaxAgeSeconds": 3000
},
{
"AllowedHeaders": [
"*"
],
"AllowedMethods": [
"GET",
"POST",
"PUT"
],
"AllowedOrigins": [
"http://localhost:3000"
],
"ExposeHeaders": [],
"MaxAgeSeconds": 3000
}
]

Depending on what you need, Chris already did 2 screencasts on this, one for Rewardful & Stripe and one from scratch, https://gorails.com/episodes/referral-program-from-scratch?autoplay=1

Yes, would love an affiliate program screencast!