Hi @tieudoan208 - all applications are created at an entry level athlete capacity of 1, aka "single player mode". Our documentation has information about this, including a form that you can submit in order to get an increase to athlete capacity and your rate limits. 

Dear team

I was summit form but Number of athletes allowed to connect to my app still 1.  Team  consider exten number of athletes allowed to connect.
thanks so murch and this is My client ID: 124032

I was submit form STRAVA API PROGRAM SUBMISSION FORM, but my request has not been approved yet.

 Team  consider exten number of athletes allowed to connect.
thanks so murch

Have your request been approved yet?

I sent request yesterday to increase number of athletes allowed to connect but nothing reply.

it spend abount 1 week from you send request. if it not approved. you can send email to strava dev

Hi - 

I've submitted the request on Aug 9th. Haven't heard back from the team.