I believe I may have followed the same path as the OP and arrived at the same stumbling block. I completed the level tutorial and wanted to try it as a class blueprint. I have attached my progress and appear to have become stuck at the same point as the OP.
I have built the door I want to move and two panels either side that should remain static, in the blueprint components editor.
Then I have copied the blueprint from the level blueprint in the level tutorial referred to by the OP.
Now I want to refer to the component that I want to move in the blueprint and it doesn’t like it.
I will go through the blueprint automated door tutorial that you suggested and see whether that help.
Many thanks in advance!