To get your ordered crypto into your MetaMask wallet, the provider you choose must execute transactions on-chain. This means that, as a minimum, you will need to wait as long as it takes for the transactions to be processed by the network (block time).
Once you submit your request, you can see the pending transaction in your MetaMask activity.
If your bank account was charged and there are delays in receiving your crypto, we recommend you contact the provider's support team directly. Pending purchases (not yet confirmed on the blockchain) are usually caused by the on-ramp provider's pre-authorization processes.