Thank you, all...
After completely removing JAVA by JavaUninstallTool.exe, I rebooted my Windows 10 Pro 64 bit PC, then I again installed jre-8u241-windows-x64.exe not into the default path but into newly created "c:\programfiles 2\JAVA64" path, and then I could finally successfully install REW_windows-x64_5_19.exe.
Thank you all again for your kind suggestions and instructions; now I will fully try REW especially the Wavelet delay measurement features after I would soon build my stereo 5-way (sub-woofer, woofer, squawker, tweeter and super-tweeter) multi-amplifiers system with software crossover EKIO.