Problem with Python + API_KEY + Add user to group

[Konstantin Belenko]

Good time of day!
Please help to understand the request to add a user to the desired group.

We use the cloud version of Atlassian. And we use the request by:
url = "https://<mycompanyname>.atlassian.net/rest/api/2/group/user

I can't figure it out by myself and write a request.
I do it according to this instruction https://developer.atlassian.com/cloud/jira/platform/rest/v2/#api-rest-api-2-group-user-post
In the "Add user to group" section

I'm creating a token at https://id.atlassian.com/manage/api-tokens
I'm putting it in the Bearer: "<access_token>

in "accountId": I specify the user Id.

Where do I specify the desired group?

Or in "accountId": should I specify the group Id? Then where do I specify the user name to add it?

Please help us with this question. For a few days now, I've been tormented, I can't find a working variant.

I need to add a specific user to a specific group using python. Please tell me how best to do it, where to find the right, working example?

[Konstantin Belenko · Accepted solution]

He keeps coming back:

"Returned if the authentication credentials are incorrect or missing from the request. 401"

or

"message": "Client must be authenticated to access this resource.",
"status-code": 401