Thanks so much Rewt for your kind advice! I am still waiting for the official documents as my Prof said it was already on the way. I’d update you the status as soon as I got my letter. In case it doesn’t turn out well, I’ll definitely contact the admission teams.

I had an unofficial offer from a Professor three weeks ago. Even though he said the official offer from the University would be made for me soon, I did not hear anything since then. He does have some plans for me during the PhD (he wants me to write a review paper and discuss the project within this week). Therefore, I am wondering how long does it take for the official letter to be made and is it normal for the process to take longer than 3 weeks? My PhD will start in October which I really needs to apply for visa and look for a room before hand. I am currently studying abroad and my residence permit will end soon. I can't go back home due to Corona and I do not know if I should apply for the search visa in case the offer would come on time. Please let me know what you think about my situation. Any suggestions are welcome!