I don't know peloton, but your height won't dictate settings on a bike, instead go by leg length to set the seat height and what's feels comfy if you can adjust the handlebars up / down or in / out.
As a rough starting point with your heel on the pedal at the bottom of its stroke your leg should be straight and then when you place the ball of your foot over the pedal axle you should have around 30 degrees of bend at the knee joint. Obviously thick heeled shoes will complicate this.
Once pedalling you should not have any rocking of your hips (iliac crests).
Please tell me you were wearing padding cycling shorts designed for females!!!
Trainers are not ideal for cycling in, but it is doable as long as they aren't trashed.
Saddle covers hide a poorly fitting saddle, saddles are a fine art in finding a comfortable one as we are all different.
Saddles can be measured in width which relates to your sit bones (ischial tuberosity) width, a proper bike shop will assist with figuring this out, if you have a Specialized Concept Store near you try them for advice.
Static cycling is very demanding on your contact points particularly those on the saddle, breaking it up occasionally with coming up off the saddle for a few seconds will help relieve some pressure.
Building up some tolerance helps, keep it fun and don't feel pressured to stay on if it's uncomfortable.
Buy a big fan from Screwfix!!!!