You have to add the external user into aad and then only you will be able to access the devops page for that external user.
How to fix access error 403 for dev.azure.com\MyOrganization for external member
Created a new organization "dev.azure.com\MyOrg".
Added accounts from my company.
Added one account from another company.
Basic accounts - 4, Stakeholders - 2, an account from another company (let's call "external") - Visual Studio Professional Subscription:
In Organization "MyOrg" created a Team "MyTeam" with 5 users: 4 "Basic" + 1 "external":
All Basic Accounts do not have access problems.
Problem:
An "external" user, when accessing any link dev.azure.com\MyOrg... gets a 403 error:
When accessing the link on the error page "View a list of your organization here." the "external" user sees their list of organizations, where he is listed as a member in the dev.azure.com\MyOrg organization:
When trying to follow the link on this page to dev.azure.com\MyOrg - the user gets the 403 error again (see above).
Question:
What does the admin of dev.azure.com\MyOrg need to do for this user to have Basic access to the dev.azure.com\MyOrg organization without error 403?
(in the Organization Settings I tried to give the "external" account Basic access rights - it is reset/returned after a short time in Visual Studio Professional Subscription)