Did you not set one in the installer? I'd recommend you get in touch with a consultant or IFS support as I don't think posting passwords publicly is a great idea. 

When installing the application password was not asked for the user Administrator . So what is the procedure to get the default password for the first login of the PSO Application.

Create a support case and they will provide it to you. 

I can confirm this is the correct approach,  for security reasons the default Administrator password is not published with the documentation but by raising a support case it can be supplied to you.  Once logged in you can change it as desired.