Translation:

According to probability theory, a number must come once every 37 or 38 spins (on average) depending on the type of roulette. This, as we know, is virtually impossible to happen in a brief sequence of spins, therefore it's only normal that more than 1 number repeats within a sequence of 37 or 38 spins.

Likewise, we can say that beyond the existence of 2-time shows (repeats), there are 3-time shows within this brief sequence, which is absolutely normal. The abnormal would be for this not to happen.

So far, so good. Based on this principle, the Fortress is based on waiting for the numbers that repeat within a sequence and bet only on them.

You must bet straight-up only on number which have repeated once, spin after spin, until one of them repeats again and generates a positive balance in chips. Once this target win has been achieved, a new sequence is started without considering the repetition from the previous sequence.

Let's see the following example:

17, 2, 00, 29, 19, 26, 23, 24, 11, 10, 36, 35, 5, 28, 7, 28, 33, 10, 5, 13, 9, 13, 17, 19, 5, 2, 26, 16, 25, 35, 6, 35, 10, 3, 31, 36, 34, 1, 8, 4, 14, 34, 14, 36, 7, 11, 34

The first number to repeat is 28 (highlighted in red), then you start to bet on it straight-up, spin after spin. Then the following numbers repeat: 10, 5, 13, 17 and 19, then 5 repeats again (highlighted in blue).

Until then we were betting straight-up on 28, 10, 50, 13, 17 and 19. Making a general balance there's a net gain of +8 chips.

In case that the second repetition would have lasted more spins to appear, you must be careful to plan your wagered amount on each number, so the hit from the winning spin compensates the losses from the previous ones.

After the winning spin you start again from scratch in a new sequence, absolutely independent from the past one, which has its winning spin on number 34, to get a net gain of +9 chips.

The complementary "Humble But Real" system is worth a read too.

The probaility do not works, nobody has seen 37 unique numbers. The matter of fact is the probability of a repeater increase after every spin. Just think all numbers has shown except one. The probability of a number hit is 1/37, which mean the probabillity of a repeater then is 36/37. It is no magic it in the pure math, and some math guys do not think so far.