How long will it take to flash a51_dtul?

Dear support;
I received following firmware from xtc2 support and tried flashing XTC2 software but it is about 3 hours and still not finished.I’m sure it’s not normal.I see no progree bar on device display but soft progress bar is moving very very slow.
Is it safe if i stop the process?
Besides i tried to install rom via sd card but phone said fail to flash coz of large file size.How can i safely flash this zip file please?