The courses taken at the partner university must have a scope of at least 24 ECTS per semester. This can also include non-subject-related courses (language courses, seminars on local culture, etc.).
After the mobility, you must be able to prove (via your ToR) that you have successfully completed at least 15 ECTS per semester at the partner university. If this is not the case, you may have to pay back your Erasmus+ grant.