re: "Does anyone know how to respond to a client's review?"
Easy answer:
Don't.
The official answer is here:
https://support.upwork.com/hc/en-us/articles/211068448-Dispute-or-Respond-to-Feedback
BUT:
Before you go and respond to a client's review (feedback), you NEED TO KNOW THIS:
It is usually a mistake to do so.
Most responses make things worse.
Most responses cast the freelancer in a bad light.
When more experienced freelancers look at the responses, they shake their heads in dismay. It is a common beginner's mistake to respond to a client's review.
You may still do so, but please feel free to talk it over here in the Forum a bit. Other freelancers will be happy to provide advice before you add something to your profile page that you (a) can't remove and (b) will regret.
