The Harris Agency interview questions

Call/interview was very brief. Manager just asked me about my background and what I was looking to gain through the internship. He told me that he'd like to have me in on a couple projects. He mentioned that he needed to check in with his supervisor to confirm the details of the internship - paid, unpaid, part-time, full-time, duration of the internship - all details you would think you'd already have organized before posting the position. I never received a call since then. I sent a follow up email a week after the offer to check if the details were gathered. He replied on saying he was still working on it and would reach out to me once it is all confirmed. It is now 6/30/20 (interview/offer was on 6/12/20) and still no word. During that time, I was able to interview with another company, wait a week for the results of the interview, and accept said offer. Although the manager himself was nice to talk to, I find it frustrating for a company to post an opening for an internship, proceed with an interview, offer the position, but not have any details lined up for someone to accept the position. My opinion is that the posting on Indeed was premature and should not have been posted until the details mentioned above were set.