No matter what it usually takes 2-5 (sometimes 3-7) working days for refunds to come through from online vendors due to how banks process these refunds. They can't make it instantly appear in your bank account. Of course that doesn't mean the website isn't a scam, but it also doesn't mean it is just because they've advised you it will take a standard number of working days for a refund to come through to you.
Also just because a refund takes a while after that date range doesn't always mean it's a scam (although can indicate that). I've had issues with e.g. John Lewis taking weeks to process a refund due to issues on their end, and they're definitely a legitimate business!