403 error means you don’t have access to that specific Style Guide, Project or Library. A user needs to be invited to every project to be able to access it. Another reason could be that Targets have been set and you don’t have access to the content (only Enterprise accounts have Targets).
What you can do:
Check with the person who sent you the link if you are invited to that Style Guide, Project or Library
Contact your Account Admin so they can check if you have access to the Style Guide and who can invite you if necessary
The Owner or Editor of the Style Guide can take the following steps:
Open the/Style Guide/Project/Library
Click on the left Powerbar on the Team icon
Check if the user is invited - search in the list or see what groups are invited
On Enterprise plan, check if no Targets have been set on the document that returns 403 for the users
The Account Admin can take following steps to check user’s permissions:
Go to User Management page
Search for the user
Under the suitcase icon, check the permissions of the user - individual and group based
Check if the Style Guide in question is on the permissions list of the user
If you need information on who the Owner is of the Project or the Account Admin, you can reach out to the Frontify Support Team. Let us know the email address of the user and the link where you or the user is trying to access the Project.