please try creating the Engineering Sample Model by using a model template. Do the following:
1. Click File > New...
2. In the Model template list, select Engineering Sample Model - Sample Model.
3. Click OK.
I believe you are referring to the First Steps tutorials available in Tekla User Assistance?
To be able to access the Engineering_Cutback autoconnection, ensure that you have chosen the role All or Engineer when you are opening Tekla Structures Learning and choosing your set up:
Do you have the latest Tekla Structures Learning installed (Tekla Structures Learning 20.0 SR2 - available in the Download section)?
Are you using the Default environment when you are choosing your setup (as shown in the image above)?