OK, so I've got a bit of experience with barcodes, let me help where I can.
The first thing you need to do is figure out what type or "language" of barcode you need. There are hundreds of different types and they are all formatted differently, it's not universal. Once that is determined, you can decide how to produce the barcode, if it's "code 39" you can use a free code 39 font, but you need to add a * before and after the text. If it's something like a "code 128" there is a whole algorithm involved and you need to use a barcode software, or a translator in conjunction with a font ( I have an excel sheet that does the translation for me)
Coreldraw can create barcodes and QR codes for you, but it's 1 at a time, if you have hundreds or more to do it is worth looking into an automated way, for example you can use print merge with a barcode font and excel to format the text properly.
What you client does with the barcodes after they get them is up to them.