That’s not a “weird pop up”, that is the normal assign footprints window. (What used to be called CVPCB, I forget what the acronym stands for but my hazy recollection is it was a hold-over from the original French that KiCad was developed in (the original developer is a French person). Ah, found the meaning here: Non-devs: what do you think of the app names? - #3 by vini_i) Some people don’t use it because there are several ways to assign footprints, and an ERC check will flag missing footprints. But if you don’t use ERC for personal workflow reasons, just checking it can be a quick scan to make sure you didn’t forget to assign footprints to some symbols. Other people heavily use it as part of their normal workflow.