@Velo-city I’ve never taken the 8min test but my advice would be you will have a much better training experience if you start with a valid FTP.
That said, FTP is typically 85% to 90% of maximal 8min pwr for me. I’m sure this can vary from rider to rider.
Your 264W effort was not maximal since you knew ahead of time you were going to repeat the effort.
So 218W is most likely a conservative estimate of your FTP.
My best advice is to retest & give yourself the best chance to train well. 2nd best advice is add 10W, start training, adjust +/- 5W depending how workouts go.