This summary is not the rule. The rule text controls.
Here's what this rule means for people involved in mediation.
If you and the other side pick your own mediator, you can agree on how much they charge. You have control over that rate since you're choosing the mediator together. But if the court appoints a mediator for you, that mediator can't charge more than their usual rate. This protects you from being stuck with a surprise high fee when you didn't get to choose who ran the mediation.
As for who pays, the rule sets a default: both sides split the mediator's fees equally. This means you and the other party each pay half, unless you agree to split the cost differently or the judge orders a different arrangement. For example, a judge might decide one side should pay more if that makes sense for the situation, or you and the other party could work out your own payment split if equal shares don't work for you.
The main point is that mediation costs shouldn't come as a surprise, and nobody should get overcharged just because a judge picked the mediator instead of the parties themselves.