I would like to know if it is possible for me to set up a vault with Crytomator through a free gmail account, if on the same notebook I already have Google File Stream configured with a corporate G Suite account (enviroment Windows)?
Cryptomator is independent from the sync software. It just creates the encrypted files. The sync is done by the sync client of the storage provider.
So if you are able to set up Google’s backup and sync app with your free google account (parallel to your corporate G-suite sync app), then you can of course sync your vault files to that online space.