Can't install upgrade from Ver 8.5 to 8.8

[justnettled]

Hi I am running the following
Software:
SilverFast Ai Studio 8
Installation type:
Standalone
product:
Plustek OpticFilm 7600i
Language:
English
Operating system:
Mac OSX 10.11

I have been trying to upgrade my Silverfast version from 8.5 to 8.8. I have attempted 5 times using different methods including from within the app using the 'automatic upgrade' and also via the download. Each time after extracting for approx 60 minutes and entering the computer admin account username and password twice at prompts, the install fails with the message similar to 'permissions have not been granted'. Can anyone assist resolving this problem. To obtain the exact error message will take another hour waiting for the install to fail again, so I'm hoping this has happened to someone else and is recognised.

[LSI_Ketelhohn]

Dear customer,

Did you make sure that SilverFast was closed when you installed it?

Otherwise try creating a fresh administrator user in the OS X System Preferences/Users&Groups.
Then log into that account ad try running the update there.

Kind regards,
Arne Ketelhohn.