How to bind attributes to a product?

Question

WooCommerce

Hello !
There are two files for import in one attribute in another product (combining these files will not work)
I uploaded everything to the site through the WP all import plugin - I didn’t find in it the assignment of already existing attributes to loaded products, maybe there is none
The product has an arbitrary field with the value that is in the file with the attribute
How now to assign attributes to the product (attributes 400 product 20k.) ?