What software can I use to encrypt all files that are copied out of the system(USB, network, email,...) such that only systems with the same encryption will be able to read the files. OS is Windows.
If you want to use a password, there are many options. VeraCrypt is one of them and perhaps the most reliable. You can create a key file in it and prevent the data from being decrypted on any system that has no access to that file.