You need to install the extension from a local source but this was available during the alpha and the below link is no longer working
https://firebase.google.com/docs/extensions/alpha/install-extensions_community#install
The specific extension does not seem to be available on the Firebase system:
Error: The extension reference
'firebase/firestore-natural-language-processing@latest' doesn't exist.
This could happen for two reasons: -The publisher ID 'firebase'
doesn't exist or could be misspelled -The name of the extension
version 'firestore-natural-language-processing@latest' doesn't exist
or could be misspelled
For the current beta from the cli tool I found the following:
First, clone the git repo of the extension:
git clone git@github.com:FirebaseExtended/firestore-nlp-extension.git
then run the following commands to build the project:
cd firestore-nlp-extension/functions
yarn add -D rimraf
yarn build
cd ../..
and then to install this extension, run:
firebase ext:install ./firestore-nlp-extension --project=YOUR_PROJECT
if you get a path error you might need to find the right path such as:
firebase ext:install ./firestore-nlp-extension/functions --project=YOUR_PROJECT