You can’t send the client id as a querystring param, you have to send it as the Client-ID header, as shown in the example https://dev.twitch.tv/docs/api/reference#get-streams Also you can’t use multiple ? in a querystring, you use the question mark symbol once to indicate the start of the querystring, and then an ampersand & to separate separate parameters.
To see the follower count you would use the Get User Follows endpoint https://dev.twitch.tv/docs/api/reference#get-users-follows with the to_id param that is the id of the user you wish to see who follows them.