Some of the server using CloudLinux service and set a limit value too low for I/O, IOPS, and CPU. These all limit make RVsitebuilder setup gets stuck. You can check the configuration at your left/right bar on your cPanel account.
This case, please inform your hosting provider to set unlimited of those limited values for this user to let RVsitebuilder setup success.Go to WHM(root) -> Server Configuration -> CloudLinux LVE Manager -> select the account and click Edit -> Then, apply Do not limit.
And DO NOT forget set it back to limit once RVsitebuilder is completed.
Admin