I have been having the same problems and this is what Topaz sent me and it works. I'm on an iMAC 10.10.4:
---------------------------------------------------------------------------------
I am sorry you are having issues with your Topaz Labs plugins!
Please try the steps below:
Open Finder
Navigate to Mac HD / Library / Application Support
Highlight Topaz Labs
Hit Command + I (for Get Info)
Click the Lock icon at the bottom right hand corner of the window pane that comes up, enter credentials
Make sure that your user and "everyone" has Read and Write access to the Topaz folder
Click the Cog Wheel icon and choose "Apply to enclosed items" <— This is a very important step, do not forget to do this!