There is no limit by cryptomator itself.
Windows WebDAV does only allow 4GB files because it’s handles as FAT.
To avoid this you can try the Cryptomator Version 1.4 Beta2 and Switch the Network Interface from WebDAV to FUSE.
You also may experience the following Windows WebDAV issue: The available space of the WebDAV network drive is your free space on your system partition. No matter where the vault is actually stored.