Use with Typesense cluster shared by other sites

At the moment, you cannot use the module to point to an existing collection (because the collection is created by Drupal with the information you set in the schema tab).

If a collection with that name doesn't exist on the cluster, I don't see any problem using the module. What issues have you found?

To restrict access, you can create an API key that allows access to only some collections and use that key on the server configuration page.

Ah, now I got your point!
The module only works if the api_key used is the admin one.

This definitely needs to be addressed; the module must work (with some features disabled) even when configured with a low-permissions API key.

Now, a non-admin key can be used to configure the integration. Of course, the key must have at least access to manage the collection(s) and the documents.