Jmeter - Ramp Up Time vs Constant Timer

I am trying to create a scenario where I need to hit an API with 200 unique hits(in my case 200 loan numbers).

I need 10 hits at a time for every 5 seconds

I used below values to generate above scenario

Threads: 200 Ramp UP: 300 Loop: 1

Synchronizing timer:: Number of simulated Users to Group by: 10

Constant Timer :: Thread Delay (in milliseconds): 5000

even after giving 5000 milliseconds in constant timer, I am getting 10 hits for every 15 seconds. can someone help me how to get 10 hits at a time for every 5 seconds