Verify your SSD has sufficient space for the patching process to complete.
Try closing the launcher, then right-clicking on the file and selecting Run as administrator.
PackCheck.exe or verifying your client's files through Steam / the Epic Games LauncherTry Repairing the Client.
If the issue is on-route, a VPN altering how your traffic gets routed can work around the problem.
ProtonVPN is an example of a trusted VPN service with a free plan which you can use for testing.
content.ggpk file.Deleting the .dll and .exe files in the client's install folder, then running the launcher again, may fix the issue.