The exclusionary rule does not apply to unconstitutionally gathered evidence if the police show they were acting in good faith and did not deliberately violate the Constitution.
The answer to this question is stated clearly on p. 163 of your textbook. On that page, the authors explicitly state that the statement in your question is true. This is something that is called the “good faith exception” to the exclusionary rule.
The exclusionary rule comes out of the 4th Amendment. The 4th Amendment says that police cannot conduct searches or seizures without a warrant. But what happens if they do? This is where the exclusionary rule comes in, saying that any evidence found in such a search cannot be used in court against a defendant.
However, the courts have ruled that this rule should not punish police officers if they thought they were acting properly. In particular, if they had a warrant, but that warrant later turned out to be invalid, the evidence they find should not be excluded. This is clearly stated on p. 163. The statement in your question is true.