Before installation, do this in PowerShell:
git clone https://github.com/wbthomason/packer.nvim "$env:LOCALAPPDATA\nvim-data\site\pack\packer\start\packer.nvim"
[1]
Open Neovim and run :echo stdpath('config'). The directory that shows is where you should put your init.vim file. It does not exist until you create it. [2]
Then vim into packer.lua, do :so, exit, open it again, write :so. Close, open, :PackerSync