How to receive/send messages on behalf of a group?

Question

Classmates

Installed the ok_api library.
Created a group, created an application, added an application to the group.
The essence of the task is in the header, for a start I decided to run a simple example.

from ok_api import OkApi


def main():
    """
        Простой запрос на примере метода friends.get с
        необязательным параметром типа сортировки
        (https://apiok.ru/dev/methods/rest/friends/friends.get)
    """

    ok = OkApi(access_token='OK_ACCESS_TOKEN',
               application_key='OK_APP_PUBLIC_TOKEN',
               application_secret_key='OK_APP_PRIVATE_TOKEN')

    response = ok.friends.get(sort_type='PRESENT')
    print(response.json())


if __name__ == '__main__':
    main()

Got this in response:

{'error_code': 100, 'error_msg': 'PARAM : Parameter access_token specified but application is not EXTERNAL', 'error_data': None}

How can my issue be resolved? Maybe it's worth installing another library, or did I overlook it somewhere in the application settings?