Just getting Zwift working is an achievement in itself. It has more than it’s fair share of bugs.
Zwift is all about watts/kg. Why you cycle, you generate power, measured in watts. If you divide that number by your weight in KG, you get watts per kg. So if you generate 150 watts, and weigh 75 kg, you produce 2w/kg. If a friend produces that same 150 watts, but weighs 50kg, they produce 3w/kg, so will move quicker than you because their power to weight ratio is better.
With cycling, there is something called Functional Threshold Power (FTP). This is how many watts can you sustain for an hour. You might produce 500W for 3 seconds, but there is no way you can hold that for an hour. As no-one wants to do a test for a whole hour, you do a test for 20 mins, and take 95% of what your average is. So, if you can hold 250W for 20 mins, you can probably hold 95% of that value for an hour, so you FTP is estimated to be 250 x 95% = 238 watts. Divide 238W by your weight in KG and you can compare yourself to others of different weights and power.
Sounds a little complicated when I type it out, but it does work.....basic power to weight equation allows you to race people of similar ability (as well as see if you’re improving if you can improve your watts/kg).