Your signed documents are what make your estate plan come to life and be legally valid. If you have printed and signed the documents, you need to store them in a place they will not get damaged by fire or flood and ensure your executors (initial and backups) know where to find the documents.
If you have executed your documents online with an online notary, store your digital PDF files in a safe and accessible location. It's best to put them on USB thumb drives, then store the drives in a fireproof safe along with a second location as a backup.