You should be asked when installing NVDA for the first time (note: for the first time, not during an upgrade) whether you want it to start with Windows or not.

If you are trying to change NVDA already installed so that it does start either before logging in with Windows, or afterwards if there are multiple users on the machine, open NVDA Settings (NVDA+N,S) and the General pane should be open by default.  In that pane are two checkboxes:

1. Start NVDA after I sign-in
2. Use NVDA during sign-in (requires administrator privileges)

Presuming you're using a Windows 10 account with admin privileges, check whichever checkbox describes exactly when you want NVDA to start speaking.

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Brian - Windows 10 Pro, 64-Bit, Version 20H2, Build 19042  

The depths of denial one can be pushed to by outside forces of disapproval can make you not even recognize yourself to yourself.

       ~ Brian Vogel