Good afternoon, Denis.
There are several options:
1. In the posting action, specify the default warehouse
http://prntscr.com/utd4waThen all products will be posted to the selected warehouse.
2. Through an additional process field.
You need to create an additional process field and write in it the name of the warehouse where you will post the goods.
After that, put the action at the stage
http://prntscr.com/utd9vu in the action, specify an additional field and check the box that I marked in the screenshot.
After that, when you go to the stage where these actions are, all products will be assigned a warehouse that you specify in an additional field.