Gmail uses your MATC Email Credentials to login.
Students Email Credentials use your MATC Account username followed by @gmatc.matc.edu
Employee Email Credentials use your MATC Account username followed by @matc.edu
Students: https://mail.google.com/a/gmatc.matc.edu
Employees: https://mail.google.com
If you cannot login to Gmail you should first try logging into Password Manager to see if your MATC Account is working.
Password Manager
If you can log into Password Manager and still can not log into Gmail please log a service ticket with the error you are receiving.