Can I sell music that you have transcribed for me?
That depends on whether or not you are the copyright controller.
If you control the copyright, it’s entirely up to you what you do with the transcription we have prepared for you. Because you have paid us to do the transcription, we have no entitlement in relation to copyright of the transcription, and will make no claim.
If you don’t control the copyright, then you must obtain the permission of the copyright controller to sell the transcription. If they give you permission, it is likely they will ask you to enter into a licensing arrangement wherein you pay a royalty for every copy sold.
If you do not control the copyright, assume that you cannot sell or distribute the transcription without permission. If you sell the transcription, you will probably infringe copyright and may be subject to legal action by the copyright controller.