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
โGeneral
โManage 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