You have 2 options:
1. First create relationships between tables and then build a View based on these tables. In this case when you create a View, on the View Properties screen, the relationships are build automatically.
2. If relationships are not set up and you join tables in a View, you should choose the fields to join tables manually on the View Properties screen.
Also, please note that you may find some helpful features only in the Relationship Settings. For example, Enforce Referential Integrity between parent and child table, Display value instead of the ID on the DataPage level.
Here is the article about the Relationship Settings https://howto.caspio.com/tables-and-views/relationships/relationship-settings/
Hope this helps.