How to upgrade and activate an existing installation of Windows 10 Pro to Windows 10 Enterprise E3/E5 purchased as a subscription in CSP channel
We have prepared instruction for setting up your CSP subscription account in your current Windows installation.
Click the Windows logo, and then the Settings icon
In Settings, go to Accounts.
Click Access work or school> Connect.
On the Set up a work or school account dialog, under Alternate actions, choose Join this device to Azure Active Directory(Required!).
On the Let’s get you signed in page, enter your work or school account > Next.
On the Enter password page, enter your password > Sign in.
On the Make sure this is your organization page, verify that the information is correct, and click Join.
After the reboot, select “Other User” and enter your account in Office 365