Scenario
You have an invite that came from “no-reply@sharepointonline.com” with the text similar to
“Here’s the site that John shared with you.
Go to Project Apollo
Follow this site to get updates in your newsfeed.“
Everything looks OK, you know the person inviting you and the name of the project makes sense to you as you already discussed it with John.
But when you You are trying to follow the link – you are getting the error message:
Something went wrong
The organization that owns this resource has a policy that prevents access from people in the domain you’re currently signed in to. If you think you should have access, please contact the person who sent you the link to this resource. 
Reason
The reason is misconfiguration in Microsoft 365 SharePoint Online tenant you got invite from.
To allow external collaboration – admin must configure it at tenant level and at site leve.
So what happened is: at tenant level external access was limited to specific domains, but at site level that limitation was not set.
Solution
That’s the only you can do. The change must be done by other company admins.
SharePoint Online External Sharing Misconfiguration )