You need to kerp the initialize popup open to let Bubble detect data first. Did you tried this? Once is detected , you need to remove /initialize in url
Thanks. Your main issue is that you are on free plan and this doesn’t let you expose API endpoint.
Test in a tool like Insomnia or Postman and you will get something like:
{
"error_class": "Unauthorized",
"args": {
"code": "1622382986106x959992887638708700"
},
"message": null,
"translation": "This application does not expose an API. Please upgrade your Bubble subscription for your API calls to run."
}