I decided to comment here as well as this might be beneficial for the community.
In short: I guess the reason for this problem is that API structures its response in a way that Adalo can’t understand it.
As I see, what you need is the values from “responses” (each response represents an entry in the collection). However, API returns “responses” as an array without unique IDs.
However, there is no any unique ID in each “response”. According to my knowledge Adalo can’t handle such responses in external collections. There were several posts on forum about that - can’t find them right now.
As for the workarounds I can suggest:
if this is collection will be used like “static” (no data changes), you can try to download it from the source to some place like airtable, and then connect it to Adalo
there might be a possibility to use some 3rd party service like Integromat to form responses recognizeable by Adalo. Though this could be costly.