Related products are meant to be purchased in addition to the item the customer is viewing. Simply click the product to place it in the pos order. The placement of the Related Products block varies according to product searched.
1) You will receive the link to download the zip file of the module pls download it.
2) Extract the zip file, you will see folder named ‘pos_product_suggestion’
3) Copy and paste this folder inside your Odoo Addons path / Custom Addons Path.