What happened to apps.ubuntu.com?
Solution 1:
Unfortunately, Ubuntu Software Center was discontinued in 2015. It was replaced with GNOME Software (rebranded as Ubuntu Software) - so unfortunately the old links to apps.ubuntu.com do not work anymore . The new standard for software from an app-store like interface under Ubuntu is "snaps" from snapcraft and not deb packages any more - that's why you get redirected.
See also the last paragraph of this answer here.