To run Automatic1111 in Colab you can use any of these two
The first one is more friendly, and there should be some youtube videos explaining how to run it.
You can use this extension: https://github.com/camenduru/sd-civitai-browser
Or you can use, this comand: "!wget [CivitAi download url] -O /content/stable-diffusion-webui/models/Stable-diffusion/[name of the file]"
Well, the last part depends of the kind of model, because not all goes to that folder, but you get how it works.
Keep in mind that if you want to use the PT files, you need to completely restart the Automatic1111 interfaz, so it can detect them.