For a limited company, ZUS is paid on salaries. So yes, if the person in Poland is paid, the company is liable for paying their ZUS contributions, both employer and employee.
If you only receive payment through dividends, then you won't have any personal ZUS liability.
You can be a director and not draw a salary, so you wont need to pay. But an employee will need to have ZUS paid. There are ways shift the accountability to the employee but the fact remains that someone will need to pay it, whether its your company or the employee, so it would need to be figured into take home pay.