Canvas does not have the ability for instructors to add individuals with non-affiliated email addresses to their course sites. To add a non-UCSB User the department you are affiliated with will need to create an Affiliate UCSBnetID for the individual. These Affiliate UCSBnetID accounts can be created by Delegated Department Editors (these are usually department Business Officers, IT Staff or other departmental staff). The full list of editors for each department can be found at: https://www.im.ucsb.edu/iam/viewdde
Once the department has created an Affiliate UCSBnetID for the individual they can then log in at https://www.canvas.ucsb.edu/ using the UCSB Users option. Once the individual has logged into Canvas you will then be able to add them through the steps here.