Once you have the Nik Collection filters installed, follow the steps below to add them to PaintShop Pro 2018.
1. Launch PaintShop Pro 2018
2. Click File, Preferences, Workspace and select Complete if not already selected.
3. Click File, Preferences, File Locations
4. Under File types:, locate Plug-ins and click Add
5. Browse to C:\Program Files\Google\Nik Collection and click OK
6. Click Ok again to close the File Locations dialog box
7. From the PaintShop Pro 2018 main menu, click Effects, Plugins and you will find the Nik Collection
You may now select the plugin of your choice