I don’t know the specifics of Salesforce but maybe you can answer this question: Can you navigate and interact with Salesforce storage via Windows File Explorer? Maybe similar to Dropbox (as a local sync folder) or maybe as a network share?
If yes, you can use Cryptomator on that. Here is a guide to give you better sense of how Cryptomator works.
If not (so the storage is only accessible via a web browser or some propietary application), it probably won’t work with Cryptomator.