To add Bridge to Logic Pro, first, make sure that you have installed Splice Bridge via the Tools section of the Splice desktop application.
Make sure you have installed the component (AU) version of the Bridge plugin, as Logic isn't compatible with VST3 plugins.
Then, add a new Software Instrument track to your project in Logic. Under "Details," select "An Instrument Plug-in." Under "Instrument," select AU Instruments > Splice > SpliceBridge > Stereo.
If the Splice Desktop App is open, Bridge will automatically connect once you've added it to a MIDI track in Logic:
For more information on using Bridge with Logic once it's been installed, check out this article: How to use Splice Bridge