OK. Let us review something.
You gave him something from Canva where you have PRO or ENTERPRISE account, correct?
Both of these accounts give you permission (licenses) to sell the work created in Canva but does not give you the right to resell original unmodified artwork.
If you gave him something from Canva and you only have Free account then it is all against Canva TOS. This is just part of it:
If you want to use any of Canva’s Stock Media, you have to pay to obtain a license or hold an Eligible Canva Subscription.
If you pay for a One Design Use License, then you can only use that Pro Stock Media in one of your Canva Designs. While the license allows you to change aspects of that specific Canva Design (such as colours or text), you may not Magic Resize the design or edit the PDFs, PNGs or JPGs you will need to pay for another license (unless you hold an Eligible Canva Subscription – in which case you can Magic Resize to your heart’s content!)
So if you are selling artwork made with Canva and you did not purchase a license for them, it is against TOS.
If you are selling artwork made with Canva you can not share source file, the license is only valid for one time one design one client.