Please note: Astra is only included with the Creator and Creator+ Splice plans.

Install Astra directly from the Splice desktop client.

Once installed navigate to FL Studio go to:

Options
​General
​Manage Plugins

On the left, you can add plugin search paths, add the location you installed and hit Start scan. The default installation path is:

Astra:

C:\Program Files\Common Files\VST3\Splice\Astra