How can I access multiple Dropbox accounts on my computer?

Complicated scenario. I could use advice on getting my Dropbox accounts nicely aligned on my File Explorer again, after a disaster with the “Team” format.
After having an issue with joining a Team, I need help getting access to and moving items between three different types of Dropbox accounts that I know have. To explain, I’ve used Dropbox for personal use for several years. Now, I have to deal with two other accounts.
1) my personal account; some of which I want only online and some of which I want to sync with my computer regularly. I use my personal email “A”.
2) an account that is owned by another but to which I have ownership access, not a “team”, but a a small organization of which I am a director. The organization owns the account using its own email and identification which I use to access that account. Email “B”
3) an account that is part of another organization, not the same as ‘2'; I have access to the Team folders and I control of one of those folders through a second email that I own, “C”.
PROBLEM 1: At one time, Accounts 1 and 2 were accessible through my File Explorer. I could move files from one to another easily. Then, I joined the Team “3". By accepting the invitation to join the Team, it sucked up all my files, closed my personal account. The only solution to undo this was for the Team Administrator to delete me. Then, I had to wait a week + 1 day to reactivate my personal account. Once I did that, I could copy the folders specific to the “3" to it.
However, I cannot get access to “2" without changing identities and I cannot now move files back and forth from “1" and “2" as I could before.
PROBLEM 2: I sent an invitation to the officers of “3" to be able to View our chapter’s folder in the Team account. Dropbox responded that each needed a ‘business account’ to view the folder – is there no way to give Viewer access to people who do not have Dropbox accounts? (At one time, one could).