Manage Credits, Add Credits - option missing?

I’d like to look into adding customer credits but when I try and follow these instructions, I just don’t have the “manage credits” option available - can’t see it anywhere. Is it hiding? Is there a website section missing? Is this an old article referring to a now-defunct feature?

https://documentation.vin65.com/Contacts/Contacts/Credits

Our account manager added this feature for us - thanks Janne!