Some time ago, the Strata website structure and hosting servers changed. This broke the “Check for Update” in CX 7.5 and earlier versions. Attempts at redirection of the URL for the “Check for Update” mechanism in these versions have not been successful.
No patch updates were released for CX 7.5.
The current version on the Mac and PC is Design 3D CX 8 (v8.2.2). The CX 8 upgrade can be purchased at the Strata Store.