What your looking to do within Shapr is impossible with STL imports. But there are workarounds you can try.
If you open the STL in Blender you will be able to do what you want, align, get dimension info and such. But using Blender is another challenge.
You can convert the STL to STEP and open it Shapr3d so you can edit it and get the info you want. Here is a tutorial of the conversion with Freecad.
- Create shape from mesh
- Convert to solid and export it as STEP file
- Import it in Shapr and you will get the editing features back since now the model is solid.