Be wary of the licensing here. being on asp.net it mean for them that their library will be available to all. this license is very very expensive. You are basically giving the opportunity to create CAD to everyone on the planet.
My solution i had to go with is buy 1 licence +/- 3000$ and installed it on a server then you create an app locally on the server that will pool from a database the requests and pipe them so you only have a single license at a time and them use the _saveas command and save it locally. then once the file has been created by autocad locally THAT file is totally legal to send around without licensing issue.
So you page can just push in database the data, attach a callback to let the user do what he wants. once the process is finish have it trigger the callback and the client will go get the file and download locally.