Your career site isn’t about selling a product or service. Your employer brand isn’t the same as your consumer brand. So why does marketing, a department with completely different goals and processes, get to control the most important piece of your recruiting ecosystem?
If they tell you it has to live on their site, on their template, with all content changes run through them, I suggest you simply suggest a fair and equitable split of the pie: they can run your website if you get to run their budget.
Seems fair to me.