Hi Dario,
We don't create tables for most users. Your event tracker will create tables in the dataset, which depends a little bit on what event tracker (e.g. GA4, Segment) that you're using.
That table not found error has two normal issues:
1. You actually don't have that table in your BigQuery. This could be because:
Your experiment assignment query isn't properly configured (pointing to the wrong table) or the table doesn't exist.
You'd need to find the table where you are logging experiment assignment events to using your event tracker and you need to ensure that your assignment query on the Data Source page is pointing to that table.
2. Another cause is that sometimes the permissions or the location of the project and where we execute queries is different from where the data are (e.g. us-west-1 vs europe-west-9).
Could you please check those 2 things nd let me know what you find?