事前設定した - The first 4 kanji comprise 2 words that have been used throughout the explanation of the Gachaporter, and essentially mean "pre-established settings;" in other words, the configuration of the device. The end, した, is a suffix used with nouns that gives them a reading like "has been done," so this fragment is "the configurations that have been done/made."
我が - Very important. This reads "waga," which means "my" or "our." The reason this is important is because some of the time, translations will need to add pronouns into sentences to make them read better in English, but this is not the case here. Ueno definitely specifies that the target belongs to her or is on her person.
お召し物 - This portion simply reads "clothes." Ueno's clothes are the target of the configurations.
である - This is a sentence ending that more or less means "___ is so."
Well, I'm already doing a lot of this, so what's one more. 出てくる - This was the verb of this sentence, found in the previous panel, which means "to come out." There's also some other stuff up here that filled out the rest of the text you see in the translation, but I'm getting tired of writing this, lol.
In the end, it definitely suggests that Ueno has controlled the situation such that the only items the Gachaporter should be dispensing are her clothing items (it doesn't even mention panties by name; the drawing implies that for us). My best guess as to why the chapter proceeded as it did is because the device did not work properly, or because, as
@RandomFanguy cleverly put it, the invention is mirroring real-life gachapon machines and simply won't give her what she wants.