Users having problems accessing external 0365 Sharepoint, okay for me (admin)

[Paul Stratford]

And this is going to be one of those frustrating ones where I don't have any error messages because they're all remote workers and all I'm getting is "it didn't work", or "it says I can't see the file". Four users, Windows 10 and OSX, Business Premium licenses.

So, CompanyX sends a Sharepoint link for a file. EDIT: External user on another company's 0365 SP sends us a link - I suppose that wasn't clear

User tries to open it. Gets prompted to login. At this point we have to presume that they read the text and chose Organisation Account. External Sharepoint says "no"

User sends an email to me with link forwarded, I login using OA with my account, I get in.

Yes, I'm admin, but I've not changed anything on our tenant that should affect this. Nor am I aware of anything I can set that restricts users from accessing third-party 0365 SP.

Finally get remote access to one user's PC, they click on link, select OA, sign in, but get message that the link has expired - they didn't get that before. It looks as if my account is now tied to that document. (I can still see the doc, and when I look at the sharing widget in the sidebar, I'm there but when I hover over it, tooltip says our user's name.)

The level of the external user, and wording of their emails, suggests that they've shared docs before and, in any case, it's worked for me.

Ideas anyone?

[#2]

@Paul Stratford  Try the below procedure and let me know your feedback.

1. Add the external user email domain into your SharePoint Online environment. (Go to SP Admin Center -> Sharing Settings)

2. Share the folder with external user(s) work accounts. If you miss step 1, then you may see 'Your organization does not allow sharing with outside' kind of error.

3. SharePoint will send an automatic email to the external user (no-reply@sharepointonline.com). Ask user to accept this invitation and create a Microsoft account if user don't have one (the username should be same as the email address to which user received this invitation). Before clicking the link in the invitation, user need to logout of all other active accounts (including gmail) on browser.

4. After step 3, the user will have access to the documents in the folder.

5. If user still have issues after creating the MS account, then you can share the URL of the folder directly thru email. Ext. user then needs to sign-in using MS account credentials to access files.

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If in case, the auto-link doesn't work after successful creation of MS account, then share the direct link of the document/folder to the external user and ask to sign-in using MS account credentials. That should work.

[#3]

@ellan1537 This seems like the standard set up for us to share our files - that's already working for us.

Are you suggesting this as a fix for my internal users accessing a third party's 0365 SP?

i.e. Are you saying that the addition of the external user (the one that's trying share their document) to the Address Book will form a relationship with the external domain that will somehow also unstick authentication of our users with their tenant?

[#4]

@ellan1537  I've edited the original post to make it clearer that we're the company receiving the link.