Can't see a sentence correction

The verb require needs a subject. The derived adjective is

required = necessary according to the rules or for a particular purpose:

We hope to be able to raise the required sum of money.

Cambridge dictionary

From this viewpoint, the sentence is correct in its use of required.

Nevertheless, the sentence leaves a lingering doubt. Required by what, or by whom? Is the requirement a particular one specified by the preceding context, or is it a general condition?

Because of these doubts, I would prefer, but not insist on, necessary, a word that does not have the feeling of an unidentified subject.

Required

stipulated as necessary to be done, made, or provided

It's clear that required functions as an adjective and not as a verb) in the OP's sentence.