To connect a new Ad account to your Meta Product Insights, you must first link it to the market. Follow these steps:
Go to the Market and Assets page and choose the most relevant market from your current markets list or create a new one.
Under the Advertising Assets tab, link your Meta Ad accounts and Catalogues.
If you intend to use the account solely for static ads, tick the box labelled "This Ad Account will be used only for static Ads".
If you can´t see any Ad Accounts, click the "Synchronize Ad Accounts" button in the top right corner.