The code in this sucks, and is not maintained, and is relatively difficult to use as it could be simplified. I don't suggest using this, find a different one instead.

There is a possibility of where I re-code this, but it's not high.

Download the repository.
Install Python (3.8-3.10 should work, make sure to include to PATH)
In the directory of the repository run pip install -r requirements.txt to install all the required libraries.
Move onto usage.

Head over to telegram's developer tools and login.
After logging in, head over to your telegram apps, and create one, enter any information you want.
After the app is created copy the api_id and api_hash, and head over to the config.txt and replace api_id:api_hash with your information.
After your config is setup, head over to the groups.txt and add the groups you want to send to. (the name after url on invite.)
After you setup the groups you want to send to head over to the message.txt and set your message to send to all the groups.
After all of that is done, you can simply run advertiser.py by either opening it, or running in cmd python advertiser.py.