The expression in question must be a translation from another language, which sometimes turns out to be a bit puzzling unless you know the source language.
Although I don't know anything the original source language, I believe what it means is that the right amount will be charged on checkout. But using "the right amount" here sounds a bit odd. So, I've changed it to "the amount payable". Since you're translating it into Chinese, you can change it to another expression that may sound more natural in the target language. I hope this helps.