Accessing Intraday Data

[SunsetRunner]

After authorization, how do you access intraday data? For example, when fetching: 

<a href="https://api.fitbit.com/1/user/-/activities/heart/date/2019-09-06/1d/1sec.json" target="_blank">https://api.fitbit.com/1/user/-/activities/heart/date/2019-09-06/1d/1sec.json</a>

the response is: 

Response {type: "cors", url: "<a href="https://api.fitbit.com/1/user/-/activities/heart/date/2019-09-06/1d/1sec.json" target="_blank">https://api.fitbit.com/1/user/-/activities/heart/date/2019-09-06/1d/1sec.json</a>", redirected: false, status: 200, ok: true, …}
body: (...)
bodyUsed: false
headers: Headers {}
ok: true
redirected: false
status: 200
statusText: ""
type: "cors"
url: "<a href="https://api.fitbit.com/1/user/-/activities/heart/date/2019-09-06/1d/1sec.json" target="_blank">https://api.fitbit.com/1/user/-/activities/heart/date/2019-09-06/1d/1sec.json</a>"
__proto__: Response

I could access the "activities-heart" json through 

timeSeries['activities-heart']

though it is 'undefined' when trying the same with "activities-heart-intraday".

[SunsetRunner · Accepted solution]

Update: Changed application type to "personal" and am able to access intraday data.