Quarries about age rule for working visa

Respected Sir,
I got selected by 3 companies of China as a yoga teacher .. I am a graduate person and got all require documents But I am little young I am of 21 and I asked many peoples some said I can get Z type some said don't know. Can you please give me some guidance if you can give me that will so great of you please I am scare that's why asking you .
Thank-you
Gaurav Vashishtha