I'm trying to get the page access token using:

graph.facebook.com/v20.0/me/accounts?access_token={user_access_token}

but i get just an empty list, so no pages in my account, but using meta business suite my account is already administrator of the page and all permissions have been granted, also i have all permits on my personal token:
publish_video pages_manage_instant_articles pages_show_list instagram_basic instagram_manage_comments instagram_manage_insights instagram_content_publish instagram_manage_messages page_events pages_read_engagement pages_manage_metadata pages_read_user_content pages_manage_posts pages_manage_engagement

What do i have to do to get the page_access_token ?