How to download Opportunities and Companies

if I make API call to either Companies or Opportunities I got access denied in API response although i have assigned all the permissions.
1. /bulk/v1/companies/export/create.json 
2. /bulk/v1/opportunities/export/create.json
returns 

{

"requestId": "1426f#19e06bb33fa",

"success": false,

"errors": [

{

"code": "603",

"message": "Access denied"

}

]

}
If API endpoints are not supported then it shouldn’t have return not supported? instead of access denied ?