How does multi-accounting work on Instagram? Are there additional restrictions?

I have a personal Instagram that I wanna grow as a personal brand as well as three different that I use for an online business. The fourth account got restricted just after I made it and I only followed 20 people. Is Instagram stricter the more accounts you use?

I've never botted and all my growth has been organic. I'd like to figure this out as ideally I could make use of 20 pages if I could do it without getting banned.

Also secondary question, I got suspended for a week on my main account for allegedly sharing my info with a follower/like service. The only service I've used is a playstore app that tells me who unfollows me and it's the same one I've seen using for the past two years. What gives?

You can use 5 accounts per device without issues.
There may be multiple reasons why you got blocks quickly on one account - maybe you made all accounts one after another and IP got "suspicious" which lowered the trust score of that account. Maybe you used 4G connection and that IP was blacklisted for spam by other users, who knows.

As for Account Compromised message - yes, even the simplest app can cause it these days.