When I added the curve circle I couldn’t see the curve display arrows in edit mode. I searched the problem in google but the answers which I found was telling press N go to Edit section and click normals.
But this isn’t the case for 2.91 or at least for me.
If you want to display or hide curve arrows in edit mode:
When in Edit mode click down arrow button next to Overlays button. (Overlay button is next to the X-ray button.) When overlays window opens click normals under the Curve Edit Mode section