Cross-posted from Adobe.

Solr is a seperate addon / extension and its best to use the adobe ColdFusion full installer. Once the you run the install wizard, you have to go to extensions and enable solr. Once the service is running, you can create your collection, https://helpx.adobe.com/coldfusion/cfml-reference/coldfusion-tags/tags-c/cfcollection.html

Do you know if I install CF outside of CommandBox if it will mess things up? Or if I install everything, can I still talk to the SOLR instance from my CommandBox instance? (This was all a lot simpler 15 years ago.)

I would not worry about the command box. It runs its own little terminal-based path-specific settings and even runs on a random port by default.