ARCADE is its own plugin (Audio Unit, VST, VST3, AAX) and does not require activation in Native Access or Output HUB. You can access it directly from within your DAW's "instruments" plugins. For detailed instructions, check out this guide:

Please try re-scanning your plugins inside your DAW and see if you can locate ARCADE. 

Logic Pro:

Here's what to do:

1. Choose Logic Pro X > Preferences > Plug-In Manager.

2. In the plug-in Manager, locate the Arcade. To filter by manufacturer, click Output in the left column. 

3. If "failed validation" appears in the Compatibility column for Arcade, highlight Arcade then click Reset & Rescan Selection.