Sentinel-1 Range-Dopper Terrain Correction repeatedly download strm*.zip but not runing.

I’m trying to run range-dopper terrain correction with a sentinel-1 image.
But after clink run, the progressing bar on the button showing downloading (it runs to 100%) repeatedly. And the pop-up message box just keep showing “writing…” and not really running.

What is the source product?

Try up to select SRTM 1sec DEM!