Hi there @Olesia Markevich,
Welcome to the Community! 
Before we dig deeper into this, could you please try creating a new conversion event in Google Analytics 4 and try loading in that newly created conversion event in the trigger by clicking on the “Find new records” button to see if the trigger will load the new sample data?
Please give that a try, and let me know how it goes!
For the beginning, I would like to use a standard event first_visit users.
Hi there @Olha Sheremeta,
It looks like the first_visit field is not able to get returned by the current Google Analytics 4. I’d recommend reaching out to our Support Team to create a feature request on your behalf.
You can reach our Support Team here: https://zapier.com/app/get-help
Hopefully, this helps.