If you are a student of one of these four involved schools, you do not need to pay for attending the module. What you have to pay for, though, is your travel, accommodation, food and your spending money.
If your school applies for Erasmus+ subsidy, contact your international coordinator to see if you can receive a subsidy as well. After all, it will help you to cover a large part of your costs.
All the four involved schools will try and help you keeping the cost of accommodation as low as possible, but some countries are simply more expensive than others. Try and take this into account when you plan your budget.