Saudi Arabia visa for football trials

I am a nigerian and I am currently in Nigeria I want to go to Saudi arabia for football trials but I don't know what visa to apply for I don't know if I can get signed by a club if I acquire  an entry visa to Saudi Arabia please I need help

And someone is saying I can't get an iqama for my age 20 I wanted to apply for an iqama so I can go into Saudi for football trials but an agent said I won't be issues iqama visa for my age he said they only issue iqama to people from 22 and above

I am from Pakistan and i want to join football academy in Riyadh Saudi Arabia , but i does not know how i can please help me