Most browsers blocked Flash Player at or ahead of its demise, and Adobe disabled Flash Player.
Flash is dead.
Not unsupported-but-still-works-slightly-dead, but dead-dead.
And with many web browsers, dead-dead-blocked-by-the-browser-dead.
Dead-dead-does-not-work-cannot-render-blocked-permanently-disabled-dead-dead.
Contact the folks running the portal.
If the portal is still serving Flash content, they're probably aware and working on this.
And Flash was never available on iPad or iPhone. (You might try spoofing that identity, if you're using Safari. Enable the developer menu in Safari > Preferences > Advanced, then Developer > User Agent > select Safari 13.1.3 iPad or whatever Safari iPad is offered, and try reloading the portal page. That might get you an iPad page, which might not serve you Flash. Emphasis on might. That user agent spoofing may or may not work.)