How to post to facebook page using facebook graph explorer API

I am trying to automate posting to Facebook using the Facebook Node.js SDK. However, for testing purposes, I thought of trying first from the Facebook Graph Explorer API UI. I was following the steps from the docs here: https://developers.facebook.com/docs/pages-api/getting-started/. I added all the permissions but am getting this error when I try posting to https://graph.facebook.com/v20.0/page_id/feed. Here is the error:

{   "error": {     "message": "(#200) If posting to a group, requires app being installed in the group, and \           either publish_to_groups permission with user token, or both pages_read_engagement \           and pages_manage_posts permission with page token; If posting to a page, \           requires both pages_read_engagement and pages_manage_posts as an admin with \           sufficient administrative permission",     "type": "OAuthException",     "code": 200,     "fbtrace_id": "AvqEpJBCdYALhe1DcGEMOee"   } } 

Here are the scopes:pages_show_list, pages_read_engagement, pages_manage_metadata, pages_manage_posts, public_profile.Idont know where the problem is because i have added all the permission needed.

I expected somrthing like this as per the documentation. { "id": "page_post_id" }