If you are not a native speaker of English, upload a copy of one of the following certificates of English proficiency. It must be B2 or higher:
IELTS: min. 5,5 points
PTE Academic: min. 59 points (person test)
TOEFL: 72 points "online"/567 points "on paper" (2 years validity)
OOPT: min. 61 points
TOEIC: min.785 points "listening/reading",160 points "speaking" and 150 points "writing"
CAMBRIDGE: FCE (B2) CAE (C1) and CPE(C2)
You could also upload a certificate from your university which states that the undergraduate course of studies you did was taught in English