Adjective for consensus

As a group, the decision was agreed upon. Although some members may not have voted for it, or may even have voted against it, meaning it wasn't unanimous, as a process the decision followed the rules and procedures of requiring a majority view.

Therefore, the group decision was concordant:

[Merriam-Webster]
CONSONANT, AGREEING

// All three tests have concordant results.
// the movie's opening-weekend gross was fairly concordant with box-office returns for that genre

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The difficulty is one of semantics and context. When a group decision is made, some people may not agree with the specific decision itself, but they may still agree with the fact that it was reached by following a process that they agree with.

In other words, from the viewpoint of an individual dissenter:

We will have to agree to disagree.
I don't believe what you say, but I will defend your right to say it.
I support and respect the process and the decision—even if it's not the result I wanted.

It's a matter of perspective.

The decision itself was accepted because it was in concord with (in agreement with or consonant with) the majority opinion.

The noun "concensus" is often used as a modifier to refer to the decision that was reached via that process. So you can say:

It was a consensus decision.

From Lexico:

[as modifier] ‘a consensus view’

I think you are correct, "consensual" is more about "with a person's consent", rather than a group decision.

Its not a single word but: "general agreement" implies that, of the unspecified number of individuals involved, most agreed to the decision; it leaves room for some of those involved to have disagreed, but suggests that the ultimate decision was agreed by a majority...