What is c9.io?
c9.io or Cloud9 IDE is a web based Integrated Developement Environment which deploys a linux container tailered to each of your project with a quota of 512 MB RAM and 2 GB storage for the free tier account.
They are asking for credit card info. How do I get it with out having to enter card details?
Step - 1
Go to Edx.org and create a free account. Hint: choose a username that you also want for your cloud9 account.
Step - 2
Now go to cs50.io, select edx and proceed with your edx account authorization.
Step - 3
Now you should see it redirect to cloud9 ide