You should be able to make an object for collision in Blender and export/import that. For this you have to use a naming convention, where your collision objects are named as follows:
Up the look of your game by using Blender models in Unreal Engine. Learn how with this simple importing guide. Note: You will need Unreal Engine 4.23 or newer to get the tools to work. For more in-depth information on the topic, check out our Inside Unreal livestreams: Blender to Unreal tools, Part 1; Blender to Unreal Tools, Part 2; Blender to Unreal Tools, Part 3.
UBX_[RenderMeshName]_##for boxes/cubesUSP_[RenderMeshName]_##for spheresUCX_[RenderMeshName]_##for your custom (convex) shapes
The ## means 'some digits', which can be used when you have multiple collision objects for a single mesh. You can find this and more info at: https://docs.unrealengine.com/latest/INT/Engine/Content/FBX/StaticMeshes/#collision
Disclaimer: I have not tested this myself with exports/imports from Blender.
If you want collision with the geometry exactly as you already made it, and don't plan to make simpler collision shapes, then you can set 'Collision Complexity' to 'Use Complex Collision as Simple' in your static mesh settings. This can be useful when you quickly want to test your scene before spending time on your collision modelling.
Blender Export To Unreal Engine 4
Hopefully this helps you with what you tried to do. Now, lastly, it might still be beneficial to export your items as individual models. Then you could, e.g., move tables in Unreal Editor when the office layout changes, or allow the player to open drawers.