What do attention tests measure?
Each measures one part of attention. The Stroop Test and Flanker Test measure how much slower you get when a distraction disagrees with the answer; the Go/No-Go Test, how well you hold back a response; the Multitasking Test, what switching between two tasks costs you; and the Card Sorting, whether you notice when a rule you were never told changes. The Schulte Table, Letter Cancellation and Visual Search time how quickly you scan for targets. The Posner Cueing measures how far a sudden flash pulls your attention, and the Vigilance Test and the Continuous Performance how well you stay alert through minutes in which almost nothing happens.
Are these the same tests psychologists use?
They follow the same classic designs, but they aren't the clinical versions. Clinical tests are given under set conditions, often on paper, and compared with norms for your age; here your device, screen and setting all vary, so the useful comparison is with your own past attempts. Where a page quotes a published average, such as the Trail Making Test's, it says which version that comes from.
Is this an ADHD test?
No. None of these tests can tell you whether you have ADHD or any other condition, and a slow or fast result doesn't point either way. ADHD is diagnosed by a doctor or psychologist, from much more than a timed task; if you're concerned, talk to one.