First of all: you can
HypnoThyroidWriter.com has an article specifically for this called Journal creation — a marriage of Canva & CreateSpace templates for Word. Apparently the author of that article even wrote a book specifically about this topic called Create stunning journals & workbooks using Canva & CreateSpace (Amazon link copied from the linked article). The most useful part of the linked online article for your situation seems to be a reply from the author to a commenter.
thanks for the useful information but I having some problems.
I created back and front cover with Canva and them I uploaded them to Createspace cover creator template. Everything looks great in the preview except that suddenly the fonts seem corrupted or rare. Any ideas?
Apparently it can happen that certain features will not work the way you would expect them to work.
Author (emphasis mine):
Did you create a whole book cover in Canva with the front and back covers, or did you upload the front and back covers to CreateSpace?
I’ve only uploaded a full cover to CreateSpace in the project set-up. I’ve never used CreateSpace’s cover creator, so I don’t know why CreateSpace isn’t accepting your fonts unless those fonts aren’t available to them.
I’m sorry you’re going through this headache, but I’d suggest creating a whole cover template in Canva, uploading your front and back covers to the whole cover template’s editing page (on Canva), creating a spine (if your page count warrants it) and following the instructions in my book for putting all the parts together.
If your book has a spine (of at least 0.41 inches, which the minimum width Canva will accept), you’ll create and upload that to the whole cover template, too, and with a spine, you can use the two-pane Canva layout I describe in the book. If your book doesn’t have a spine with text on it, though, you can just create a full cover template using the combined width and the height of the front and back cover and the spine width you’d get by using CreateSpace’s cover template generator (just to get the width measurement for the spine, based on page count, trim size, and paper type). Then you could upload the front and back covers, position them on the full cover template against the outer edges, and fill in the space between them with a matching color (Google Chrome’s “Eye dropper” extension is a huge help with this).
This supports that the answer to the question about whether you can do this with Canva is "Yes", but as the author of that article wants to make some money from their work you would have to buy the book for the complete information (I am not affiliated with the author or any of the companies involved).
Other than that the information about this topic is a bit scarce. For example this CreateSpace community thread talks about the topic, but there is only one person responding and the information boils down to "Read the requirement guide, then it shouldn't be a problem". But this thread also gives a link to the following tutorial for GIMP: Create Your Cover That one seems to give you lots of examples and it mentions a link to a site where you can find templates:
CreateSpace Cover Template Generator (emphasis mine; I am not affiliated):
This tool creates cover template files in PDF and PNG, and optionally IDML, SLA and ODG formats.
The files conform to the CreateSpace cover requirements.
PDF is a vector format, PNG is a raster format, IDML is InDesign, SLA is for Scribus, and ODG is for OpenOffice.
The InDesign IDML and Scribus SLA files contain multiple layers and guide lines.
Just choose your trim size, number of pages, and paper type, and optional file formats.
You can specify an ISBN if you want a barcode.
There is a limit to how many you can get for free, as we have made this available to assist self-publishers. If you require many cover templates, please email for a quote.