By host organization we mean company, research center, institute, university, non-governmental organization (NGO), etc.
In order to find an organization, you first need to clearly know what you want, and then start your search amongst acquaintances or teachers.
If you have not been able to find an organization by means of teachers or acquaintances, the ideal place to find it is online. Send emails to as many organizations with the same profile you are looking for as possible. Write them and explain what the Erasmus+ Placement program is. Don't forget to mention that you are a candidate for a grant and that the organization is not required to pay you a salary. After you have received the agreement in principle, you can open a discussion with the respective organization regarding additional benefits such as: accommodation, transport etc.