Pop-up blocked
Equipment List and CAD, Cut, Paint & Label open a new tab the moment you click them, so browsers do not normally block it. If yours does, the designer shows a notice with an Open Window link that opens the same page. Click it.
To stop it happening again, click the blocked pop-up icon in the address bar, choose Always allow pop-ups and redirects from https://hangarflying.com, and click Done. That allows pop-ups on Hangar Flying only. A browser extension that blocks pop-ups may need the same allowance.