Hi Henrik, Canva needs to be able to connect directly to the CMS, which needs to be available from the public internet and must have HTTPS enabled. If your CMS is on a private network or only available via HTTP then I am afraid it is not suitable.
web should not be in the URL that you use to access the CMS so we would recommend correctly installing the CMS, reconfiguring the Players for the new corrected URL path and then try Canva again https://info.domainname.nu/xibo/web