Limit your search to APA Full Text articles.
From the results list, click on the PDF or Full-Text HTML link under the article citation you wish to link from your Canvas course.
When the article appears, copy & paste the URL in your browser address bar into your Canvas course.
You DO need to include the proxy prefix in front of the APA PsycNET URL:
Your final URL should look something like this - click on the url below to go to the article: