Deposits get credited after one network confirmation which can take long depending on how much fees you paid. Although recently the fees had sky-rocketed, they are down now to manageable levels and they should not take long. If you have any other questions, dont hesitate to ask here.
Credit a deposit after one confirmation is a common standard on many platforms. Because with one transaction, it is save to credit it to an account balance for user to bet, then withdraw if they want. Usually platforms will require a higher confirmations for withdrawals than deposits. If they require 1 confirmation for deposit, they will require 2 or 3 confirmations for withdrawal plus some other conditions to avoid money laundering.
The user can read this article to understand more about it.
How many Bitcoin confirmations is enough?