Error 504 – Gateway Timeout

I tried to migrate a website(workingrand.com) to wig.wpmudev.host, it took time as the size was large. Now the wig.wpmudev.host is not loading and am getting the following error
Error 504 – Gateway Timeout
The server timed-out handling your request due to a temporary overload or long-running script.
Please try again later or contact us if the problem persists.
Can you please help me solve the issue
Akash