Apple terminated our ability to develop Fortnite for Mac back in 2020 without explanation.
After the return of iOS in the European Union in 2024, the August 2020 version of Fortnite no longer works on iOS/iPadOS/macOS and Android devices.
You can still play Fortnite on your Mac using cloud-streaming services. Refer to this article Can I play Fortnite on Cloud-Streaming services? for more information
You can find more information about current supported platforms and requirements in our FAQ: Fortnite Returns to iOS in the European Union!