Hello Velocity300 and welcome,
You should not be seeing any "activation email and password" when using your Comcast Gateway (CG3000DCR) to access the internet. You will need to contact 800-391-3000, use high speed internet technical option, and ask the technical agent to check the following:
1. make sure your CG is in the biller and in active status
2. make sure that your CG is provisioned correctly
3. make sure the correct boot-file with your speed is loaded
4. make sure that the technical agent can log into your CG, check all internal setting
Hope this helps you out.