There can be several reasons for a Google Shopping campaign not delivering ads:
Did you import your products and upload them to Google Merchant Center? Did Google approve them? More information on importing / uploading products and on product approvals can be found here.
If you have created a new Google Ads account through PrestaShop Ads, did you claim that account and did you setup payment information in Google Ads? More information on this can be found here (read the Introduction of that article).
If you created a Google Smart Shopping campaign through PrestaShop Ads, it might take some time until the campaign starts to deliver ads. To be eligible for a Smart Shopping Campaign your Google Ads account must have at least 100 users on the Remarketing list. The PrestaShop Ads module installs Remarketing tracking codes to your Webshop. This tracking code fills the Remarketing list automatically. Depending on how much traffic your Webshop has, it might take some days until the threshold of 100 users is reached.