How do criteria and weights become one score?

The arithmetic

Weights are percentages and must total 100. Each criterion gets a 1–5 score with a written justification, which is normalised and weighted into the overall number.

Ships end-to-end features   30%   4/5   =  24.0
Depth in our stack          25%   5/5   =  25.0
Works without a spec        20%   3/5   =  12.0
Production ownership        15%   4/5   =   9.0
Written communication       10%   3/5   =   6.0
                                        ───────
Overall                                    76

The number is only useful because the five lines above it are visible. A score with no reasoning attached is noise, which is why every criterion carries its own justification.

What a minimum score does

A minimum flags a candidate as below the bar you set on that criterion. It is a marker for a human to look at, not a gate.

When you disagree with a score

Read the per-criterion reasoning first — disagreement is usually about the rubric rather than the candidate. If a criterion is being read more literally than you meant, rewording it and rescoring that role is the fix.