The date your Direct Debit is debited from your linked bank account will be considered the contribution date.
For example, if the payment left your bank on 5 April 2023, it would be part of your 2022/23 tax year contribution. This is even if the cash does not arrive into your Freetrade account until 6 April 2023. However, if the payment left your bank on 6 April 6 2023, the payment would be part of your 2023/24 tax year contribution.