Your city's subscription developer api key does not works for getting POI.
Your city's normal subscription does not include location plateform. You have to buy extra location platform.
Note: even esri said 12 months free trial, however, my api key was revoked by esri once reach max 500 request quota. Free isn't unlimited free. It is 500 map click or 500 move, zoom, map free. After you click map 500 times, your api key will be revoked by esri. Here is how I fix this problem by re-generating a new api key, than you get another 500 quota.
Step 1. existing api key
https://location.arcgis.com/dashboard/
Step 2. existing api key
Step 3. create a new one
Step 4.
Step 5. tricky here, even esri saids 12 month, less than 3 months, your api will be revoked by esri automatically. So I just set expire date as default 3 months here. Set 1 year expire date does not helps.
Step 6.
Step 7.
Step 8.
Step 9.
Step 10.
Step 11.
Step 11. Free is not real free, esri impose 500 max quota
Step 13. check billing to pay after free trail
