Need some advice on my new starting job

I applied for one of the entry-level positions for a company, interview is fine, was offered the position the same day after the interview last week, and asked me to start on the 18th(coming up Monday). HR sent the offer letter on Tuesday, signed and got back from HR shortly after, HR started to ask for some personal info. After that, no one got in touch with me, neither the hiring manager nor the HR, had to email and follow up a few people and chase them around to get some updates since the job starts next Monday and no one has been in contact with me after I signed the offer letter, is this normal and I'm just too entitled or its a red flag that management might not actually care about new hires?

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