Check in this order:
1. Master status — Go to Admin → Integrations → Canva. If there's a red "not active" status, the master credentials are missing. Contact support.
2. Pop-up blocker — Some browsers block the Canva redirect. Allow pop-ups for `senly.io` (or your own portal domain).
3. Canva account — First log in separately on canva.com to verify your Canva account is active.
4. Browser extensions — Privacy extensions (Privacy Badger, uBlock) can block the callback. Try incognito.
Still stuck? Send a screenshot of the error message to support.