Having more fun and getting fitter each time

New to Zwift. Using a Bowflex C6. Still learning all the features of the Zwift app. I am feeling a little embarrassed and ashamed though. I have been getting ride ons. I thought they were generated by the app for improving my cycling. After today I saw I had six from people I do not know. I am very pleased and very flattered to get them but cant figure out how I am getting them.
How do I say thank you to those who do give me them?