Can I tag multiple articles at once?

Yes. Click Bulk actions in the article list header, select up to 50 articles, click Add tags in the bar and pick the Team tag. Every selected article gets it, for the whole Team.

Tag the selected articles

1. Open a feed, folder or Team folder in List, Card or Magazine view.
2. Click Bulk actions in the header.
3. Select up to 50 articles. Shift+click selects a range.
4. Click Add tags in the bar and pick the Team tag.
5. Press Esc twice or click the X to leave select mode.

In Column view the header's ⋯ menu has Enable select mode instead. The tag menu has a "Search or create tags" box, and Team tags carry the Team tag icon. Click a tag, or type its name and press Enter, to add it to all selected articles. A tag that some of the selected articles already have shows their count, and clicking an added tag removes it from them. Create the Team tag first, as How do I add a Team tag? shows, then tag the selection. Tagging sends no notification to anyone.

The same bar has Share with Team for channel members. To tag new articles automatically, create a rule with the action Assign tag and pick the Team tag.

Plans

Bulk actions come with Pro, which every member of the Team and Team Intelligence plans has. How do I use bulk actions? explains select mode, and How many articles can I process at once with bulk actions? covers the limit. The feature page Share one set of sources with your whole team has an overview of the Team features.