Can't access shared files on a different device. "You don’t have access to this content." message.

I'm new to Dropbox. Someone has shared a directory with me, and I've set up the Dropbox app on my iPhone and can access it. When I login to Dropbox using Chrome on my laptop, it tells me "You don’t have access to this content. You’re signed in as xxx@xxx", quoting exactly the same email address associated with the iPhone app and invites me to contact the directory owner to request access.

Do I really have to request access to see the same files using the same account every time I change device? Seems a bit silly to me.

I would ask the Dropbox helpdesk, but apparently I have to pay a subscription in order to contact them, which strikes me as an excellent way to lose new customers.