For discussing the development and usage of Checkout UI extensions, post-purchase extensions, web pixels, Customer Accounts UI extensions, and POS UI extensions
HiI can't choose Target Country and Target language, help please ?
That usually means it is not supported. For example North Macedonia is not supported.
Here is a full list: https://support.google.com/merchants/answer/160637?hl=en
Not supported ? So what should I do now to install the app ?
Maybe consider text and or display advertising in Google Ads. And wait for Google to add your country to the list.