How do i set up a rental real estate business (LLC) in QBO with multiple properties. I have a property manager who does the actual management of the properties

Let me help you setting up your business, Rbea.

You can add all your properties as customer and the property manager as class. That's the easiest way to track all transactions made by your property manager. Let's follow these steps on how to add a customer:

1. From the Sales tab, select Customers.
2. Click on New Customer and enter the customer’s info.
3. Select Save.

You can also check this article for more details: Manage your customer list.

Once done, we can now turn on your Class tracking so can add your property manager. Though, this option is only available in QuickBooks Online Plus and Advanced. 

1. Go to the Gear icon and select Account and Settings.
2. From the Advanced tab, select the edit (pencil) icon in the Categories section.
3. Check both Track classes and Warn me when a transaction isn’t assigned a class.
4. Click Save.

We can now create your class list. Then, you're now ready to track your transactions by class. We also have reports by class you can pull up if you need to review them.

I'll be right here if you have more clarifications. Have a great day!

Having been in rental real estate since 2001 let me direct you towards a better solution than the one presented by @AlexV 

Yes, you will want QBO Plus with Class Tracking but your property manager is not a class but a vendor. You would create a class for each property (by deed or property tax ID).  Since you are not considered a full time real estate professional your p&l will be reported on Schedule E one column per property.

From the monthly statement you enter info on income and expense and as assigned by property which is Class. Each property will also exist on your chart of accounts as a fixed asset.

Alternately if you choose to forgo the added cost of Class Tracking which requires Plus or higher you would in fact enter each property as a customer and enter sales receipts monthly.  However you will have to enter a receipt each month for each property whereas with class tracking all expenses and income can be entered on a single monthly sales receipt and single monthly expense voucher saving you time and effort.

Since you have a manager managing g individual units you only need to record transactions at the property level and your quickbooks company file would never need to contain tenant info

Hello,

I am working as an Accountant of a Real Estate Management LLC . Our Company has own multiple project . Now i want to project wise customers balance , bank received and withdraw , Profit and loss account .