Maybe the readme file of gogrepo is out of date, but you SHOULD use python 3 with it. I am not sure if it even supports python 2 anymore.

Hopefully you were trying the Kalanyr version of gogrepo, e.g. this:

https://github.com/Kalanyr/gogrepoc

Here are some quick instructions on using gogrepo on Windows (hopefully I got them right):

1. Download and install Python 3.x.x from https://www.python.org/downloads/

- When you install it, make sure to tick the box for letting Python to be added to the PATH, so that you can run python scripts easily anywhere in your filesystem.

2. Get gogrepo from https://github.com/Kalanyr/gogrepoc

- Click on the "Clone"-button and select "Download ZIP", and then uncompress the zip file to a suitable place in your computer, e.g. C:\gogrepo\. There should be a subfolder "gogrepo-master" (or similar) where you have the gogrepo.py script.

- For simplicity's sake, put gogrepo to the drive where you think you have enough room for your GOG game installers you are going to download. However, there are also options to download your installers to any other drives or paths.

3. Run preliminary things for gogrepo

- Open the command prompt (press the Windows key + R and type cmd) and give these commands:

pip install html5lib
pip install html2text
pip install six
pip install requests
pip install pyopenssl

cd \gogrepo\gogrepoc-master (or in whichever folder you uncompressed the gogrepo.py script)

Note: before running the following (login) command, it may be advisable to make sure you are able to log into your GOG account with a web browser from that very same computer (IP address). That way the two-factor authentication shouldn't kick in in the next command because gog.com sees you have already successfully logged into your account before from that same IP address:

python gogrepoc.py login

Follow the instructions, if you have two-step login enabled, you have to get the verification code from your email and enter it here. This login needs to be done only once, in order to get valid login cookies ("gog-cookies.dat") for gogrepo.

4. Run gogrepo.

In the command prompt, in the directory where the gogrepo.py is (e.g. c:\gogrepo\gogrepo-master\), you can run e.g. these commands:

python gogrepoc.py update -lang en -os windows

This step can take many hours, depending how many games you have in your account. It creates the gog-manifest.dat file including the details for all your GOG game files, in this example for English language Windows versions of games only. If you want some other language versions as well, I think these are the known language options: en cz da de es fr it hu nl no pl pt br ro fi sv tr ru ko cn jp

python gogrepoc.py download -dryrun D:\goggames\

This will not download anything, but only simulate it. With it you can see how much data is to be downloaded.
After that you can run the proper download command:

python gogrepoc.py download D:\goggames\

Replace "D:\goggames\" where you want to download your games. Naturally the directory must exist already.

Two additional commands you might want to try:

python gogrepo.py clean D:\goggames\

That will move any obsolete files into the !orphaned directory, from which you can delete (or keep) them at will.

python gogrepo.py verify D:\goggames\

That will verify that your downloaded files are ok (correct md5 checksums, and zip files pass the integrity check).

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Then next time you want to check and download for any new or updated files, run update/download/clean/verify again, rinse and repeat.