Adobe just released this in-browser editing tool for Muse websites- you might want to try it:
Adobe® Muse™ CC In-Browser Editing
As far as I am aware, there is no limit to how many website you can have. The 3 that you have mentioned is likely referring to 3 admins per site- but note that you can have more admins for a fixed fee.
You might also be getting confused by 5 free basic sites that come with a creative cloud subscription- so fyi, you can have as many sites as you like and the hosting fees, I believe, start from around $6-$39 per month.