To connect your PrestaShop store you need to first create your API KEY from Advance Paremeters > Webservice section.
Generate your new KEY and insert in description PRICEFY KEY just to remember why has been created.
Now flag all proper permissions in order to let Pricefy reading products prices.
categories GET
combinations All
configurations GET
countries GET
currencies GET
image_types GET
images GET
languages GET
manufacturers GET
price_ranges GET
product_customization_fields GET
product_feature_values GET
product_features GET
product_option_values ALL
product_options ALL
product_suppliers GET
products ALL
shops GET
states GET
stock_availables GET
stock_movements GET
stocks GET
stores GET
suppliers GET
tags GET
tax_rules GET
taxes GET
warehouses GET