Hi @Oskar_JF , you can invite them as a guest to your Team, as long as it's ok that they see everything else going on in that Team - chats, other files, etc. We can't invite anybody to just a single tab or a single channel. Otherwise, I'd open it up in SharePoint and share from there.
Thank you for your response Kelly. I'm creating a custom app and want to offer the user the ability to edit files (in that team) within Teams. I'm just not sure if it's possible. I know it is possible if the user just goes to the Files tab and selects "Edit in Teams" from the context menu there.