I just played 523 coin flips (49.5% chance of success with a 1% house edge). Only won 199 of them. The probability of winning 199 or fewer out of 523 is 8.9696e-8, or about one in ten million.
Their provably fair system doesn't work because they only show the server seed hash, but they never reveal the server seed of past rounds, so there is no way to do the calculation to verify that those rounds were fair.
They say the algorithm is:
$client_seed = "your_client_seed";
$server_seed = "your_server_seed";
$result_seed = hash_hmac('sha512', $server_seed, $client_seed);
$result_number = hexdec(substr($result_seed,0,10));
$lucky_number = $result_number % 10001;
echo $lucky_number;
But this is all they show you in the fairness dialog.

It never shows the server seed for the previous round, so you can't check the fairness. This is a fake PF system.
I recommend avoiding the site until they fix their PF.