If ZWCAD failed to be installed, please go to the folder of %temp%, and find the folder that has the same name with the installation package.
For example, "ZWCAD_2018_ENU_Win_64bit"(if you installed English version and 64 bits), then go to the folder msi-->zwcad and install Zwcad.msi and ZwcadLP.msi one by one.