CDN can’t be found

I’ve just installed the CDN plugin, but cannot get it working.

CDN says it can’t be found.

Shift8 CDN Debug Info

WordPress Version: 5.3.2
Current WordPress Theme: ProPhoto 6 version 6
Theme Author: ProPhoto – https://www.prophoto.com/
Theme URI: https://www.prophoto.com/
PHP Version: 7.1.1
Active Plugins:
Akismet Anti-Spam (4.1.3)
Classic Editor (1.5)
Google Analytics for WordPress by MonsterInsights (7.10.3)
Highlight Author Comments (1.0.2)
ImageMagick Engine (1.5.4)
ImageMagick Sharpen Resized Images (1.1.7)
MOJO Marketplace (1.0.1)
Post Notification (1.2.40)
ProPhoto 6 Installer (6.0.4)
ProPhoto Proofing (1)
ProPhoto Proofing (P6) (6.0.19)
RSS Feed Signature (1.1)
Shift8 CDN (1.34)
Twitter Tools (3.1)
Wordbook (0.14.5)
WordPress Database Backup (2.3.3)
WordPress Mobile Edition (3.1)
Wordpress Thread Comment (1.4.9.4)
WP Super Cache (1.7.0)
WPtouch Mobile Plugin (4.3.37)
Yoast SEO (12.8)

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