Newbie to Modding - getting errors

[nejxis]

So Basically i've been playing this game for some time now, with all 3 DLCs. Lately I am getting intrigued into modding some of the stuff to make it a more fun experience for me. So I tried to start with some basic stuff.

I want to add some buildings to the Apartments and Commercial buildings to add more variety and also sizes to be able to use a 4x4. My idea is to have one 3D model in which there are multiple blocks but in reality it is one big project with one permit like in real life. Such as this one from megapolis https://vignette.wikia.nocookie.net/meg ... 0928084746

Anyway, back to the problem. I've followed all the tutorial step by step, however I am getting an error.https://imgur.com/a/w0yGRZf

How can I fix this please? I tried using the latest stable release as well as the post-release beta, same error.