Converting unix cli command to windows

I am using gethttpsforfree.com to get my cert. I am stuck on step 3. They want me to run a command but it's a unix command and I am on windows. The command is

PRIV_KEY=./account.key; echo -n "eyJub25jZSI6...cGRmIn0" | openssl dgst -sha256 -hex -sign $PRIV_KEY

Now this won't work on cmd ofcourse. But I am not that good on cli. The closest I have gotten to get it to work is

echo -n "eyJub25jZSI6...cGRmIn0" | openssl dgst -sha256 -hex -sign accout.key

The output comes but the site won't accept it. So I assume the | is the problem because it has different meanings on win/unix cli. So I need help converting that to cmd equivalant

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