Explanation/Reference:
Explanation:
Server 1 (IPAM): Access Policy
VMM must be granted permission to view and modify IP address space in IPAM, and to perform remote management of the IPAM server. VMM uses a "Run As" account to provide these permissions to the IPAM network service plugin. The "Run As" account must be configured with appropriate permission on the IPAM server.
To assign permissions to the VMM user account
In the IPAM server console, in the upper navigation pane, click ACCESS CONTROL, right-click Access Policies in the lower navigation pane, and then click Add Access Policy.
Etc.
Server 2 (VMM) #1: Network Service
Server 2 (VMM) #2: Run As Account
Perform the following procedure using the System Center VMM console.
To configure VMM (see step 1-3, step 6-7)
1. In the Fabric workspace, expand the Networking node and then click Network Service.
2. Right-click Network Service, and click Add Network Service.
3. In the Add Network Service Wizard, on the Name page, next to Name, type IPAM and then click Next.
The Description field is optional.
4. On the Manufacturer and Model page, next to Manufacturer, choose Microsoft and next to Model, choose Microsoft Windows Server IP Address Management, and then click Next.
5. On the Credentials page, next to Run As account, click Browse and then click Create Run As Account.
6. On the Create Run As Account page, next to Name type a name for the account, for example VMM User.
7. Next to User name, Password and Confirm password, enter the username and password for the account that was created on the IPAM server in the previous procedure, for example contoso\vmmuser.
A description is optional. See the following example. Click OK to continue.

Etc.
References: https://technet.microsoft.com/en-us/library/dn783349(v=ws.11).aspx