"He drank a glass of red wine."
Translation:Il a bu un verre de vin rouge.
Bu is a past participle (drunk) and cannot be used without an auxiliary in this sentence (it would be like saying "he drunk wine").
If you really want to literally translate the preterite drank, you can use the past historic "il but", however this tense is not taught on duolingo and probably not accepted because it's very rarely use in practice outside of formal writing. It's better to use "il a bu" for both preterite and present perfect.
All you said was correct. I just wanted to highlight that Il but is (supposed) to be accepted by DL, because it's a totally correct translation. So if you want to be fancy on DL, you are allowed to use the Passé simple
You may not, because we were instructed to not teach/use it, so the passé simple does not appear in accepted translations.