Hi Alessandro @alex-oss,
To start with: Adalo External collections expect to receive an array of records from external source. There should be some unique ID for each record in this array.
What you are showing is not an array of records but rather a single record.
Judging by what I see in the docs here Create an application, you might need to use another call to get values from a table. This one might work: Search for rows - I didn’t find a classic “get all”. Putting POST request in Adalo for GET ALL type of query should work (although it’s a bit unusual).
Of course testing is required.
Hope this helps.
Best regards, Victor.