Workout cadence and power

Just tried a workout for the first time. Been on Zwift 2 months. Tried the ftp builder and followed the instructions in erg mode. Problem is gearing set too low and I was having to have a cadence of 110 plus to get any power. Also watts were all over the place: said to maintain 105 for 5 mins which I do normally on a free ride (my ftp is only 118) but it was varying widely between 80 and 130. I’m using a Wattbike atom. Any ideas?

It may help if you turn on the ERG mode!

If you bothered to read the post properly rather than being a smart ■■■■ it states I was in erg mode-that’s the whole problem.