You can just use your digital documents directly, and augment it with the few paper receipts that you might (or might not) still have to deal with. The main selling point is really document management (to me, anyway), the 'branding focus' on physical documents is probably a little misleading.

I track, using tags, whether a document is a scan or properly digital. The pendulum is strongly in favor of the latter: I use this tool a ton for natively digital documents as well. Invoices, contracts, tickets etc. all come in as PDFs anyway, luckily. I have all that knowledge at the tip of my fingers. Yes, some of those documents are scans and used to be physical paper, but that’s besides the point.

You can easily use this for digital documents as well. The only difference in my setup is a tag showing whether the document id maps to a physical document in a binder or not.