I'm on a Family plan. One member is being asked to upgrade, in order to use a shared folder.

Laguille wrote:

one of my members I share folders with has been asked to upgrade her plan to get access to these folders. Why?

Because you have a 2TB plan, they dont. Account upgrades do not benefit anybody else within a share. 

The exception to this is people are within the Family Plan and using one of the family plan's licences - they dont use quota, it is only counted once. 

Hi Laguille, 

If you are on a Family Plan 2TB ( with up to 6 members in the group), did you check if that member is already invited to join to your account. It should be you who owns the plan, and others are members. To check if that member is already added in your Family account, you can click your Avatar ( person icon or name initials) > Select Settings> Select Family or you can just click this link when you are logged in to your account : www.dropbox.com/account/family . If that member indeed is on the list, you might want to double check if he/she is logged in to another Dropbox account that is other than the email under the Family plan . You can check your total usage as a Family plan as well and you can even check how much is the total space used by that member. Hope this helps. 

Thank you.