I am no expert, but I advise you to go over this link, in which @Dan_Whitnable_Alpaca has clearly explained the limits of order/data API calls.
I am not sure if even the wildcard subscription would work. Even subscribing to 6000 symbols directly can easily put you over the data requests limit. You may want to split it into multiple requests having a smaller set of symbols to ensure that you stay within limits.
Thanks