Which plan should I get to start a business?

Which plan should I get to start a business?

Hello, I plan to develop a baseline app and sell.

Assuming each customer has 5 users, and there are 2 customers, A and B.
Does that mean I'll duplicate my baseline app twice for them?
If customer C requires customization, I'll duplicate baseline app and customize for them?
So now I have 4 separate apps right?

I would like to bill customer separately, and just give them user IDs and passwords to use the system.
In other words, I'll be meeting prospects face to face or through phone to sell my app.
Is this business model allowed by Zoho?
If it is, which plan should I purchase?

Any kind souls to advise?

Thanks,
SQ.