For Mac:
1) Please log in to the download page, download & install the AU/VST version of BIAS FX 2.
2) Launch Cubase or Nuendo, go to Studio -> VST Plug-in Manager and check if the correct path is added. The default location is: Library/Audio/Plug-ins/VST/.
3) Click Rescan All 
and wait for its completion. Make sure BIAS FX2 is in the list.
For Windows:
1) Please log in to the download page, download & install the BIAS FX 2.
2) Make sure the VST/VST3/AAX files are installed in the following paths:
If you'd like to change the install location for a specific section, please click the corresponding "Browse" button on the right side.
*We'd strongly recommend keeping the install location as default.
3) Launch Cubase or Nuendo, go to Studio -> VST Plug-in Manager and check if the correct path is added. The default locations are as below:
32bits - C:\Program Files (x86)\VstPlugins
64bits - C:\Program Files\VstPlugins
4) Click Rescan All 
and wait for its completion. Make sure BIAS FX2 is in the list.
5) If the steps above are not working, please try to re-install the BIAS FX 2 at this location, (instead of the default location): C:\Program Files\Steinberg
Then, locate the file: BIAS FX2.dll file and copy/paste it into the VSTplugins directory for Cubase (mentioned above in step 1).
How to setup and record in Cubase/Nuendo?
How To Record Audio using Cubase Pro 9