I just resolved an issue I was experiencing getting “Account Linking Failed” during step 6 via the instructions on the page.
I found my solution and wanted to share it because I did not see it mentioned anywhere.
On my android phone, I have to accounts linked. I was creating my Google project on one account and Google Chrome on my phone was syncing to my other account. Once I switched my Google Chrome to sync with the account I had created my Google project on, the service (my Google project) was added correctly when Google Home opens up Chrome to authenticate the service to your Google account.