Adobe Connect

You don't need to purchase anything to use a Connect room. The meeting should be accessible through a URL and will run in the Flash Player in your browser. Has the provider of the class given you any information about joining their classes? You may want to start by reaching out to them and see if they have any guidance or documentation to leverage.

If you do run into an issue, you can post it here.

You should talk to the instructor of the course to see if there are any arrangements for a group hosting or other plan.  Otherwise you will need to talk to someone at Adobe about purchase options. 

You might also try using the Buy option on the product page.  It links to a page that describes the various options.