Hi there, thanks for reaching out to the community!
It sounds like there is a permissions-based issue, as in order to be able to use or access a main component, you would need to have access to the file where the main component lives.
I’d recommend you to reach out directly to the support team by filling out this form here. They can check the permission right on our backend and investigate it further.
Be sure to use your Figma email account, include the email address you are logged in with when trying to access this file, send them a link to the file and to the component where you are experiencing this issue and, a link to the library file, where the main component lives. (More information can be found here: Share or embed your files and prototypes. Thank you