If you need to be added to a new company, send the Owner or Admin these instructions on how to invite you.
The words "Account" or "Company" can be used interchangeably in 90. A new/separate account will have its own unique data and users, so absolutely no information is transferred between two accounts. Billing is also done separately.
Need to create a new company?
Go to the My Account page by clicking on your profile icon in the upper right. From there you will see this create account option in the bottom left of the page.
This will take you to the page to create a new company, and when you do it will automatically be added to your list as shown below.