Right now, Google drive api does not support content downloading for native google drive files (google docs, sheets etc.), so you cant download content (current or of an old revision), you can only export it to a different mime type.

The "Daily Limit for Unauthenticated Use Exceeded. Continued use requires signup." is misleading. It implies you've reached some kind of quota, but that is almost never the case.

The Drive quota for unauthenticated use is ZERO. So what the message is really telling you is that your Drive request isn't carrying an Auth token. You should trace the http and you will find that the requests that are failing are missing the Authorization header. As to why, well that's an exercise for the reader.

403 Forbidden

Means that the user accessing the link does not have permission to access it. The user would need to be logged in to access it. You can try setting the file to public but the link will probably still expire after a time.

Also there is a recent security change which may be effecting you Resource keys

Google Chrome as well as Mozilla Firerfox both provide an option to copy download link specifically for cURL. This option will generate cURL with all required things such as User agent for downloading things from the side. To get that,

1. Open the URL in either of the browser.
2. Open Developer options using Ctrl+Shift+I.
3. Go to Network tab.
4. Now click on download. Saving file isn't required. We only need the network activity while browser requests the file from the server.
5. A new entry will appear which would look like "download.aspx?...".
6. Right click on that and Copy → Copy as cURL.
7. Paste the copied content directly in the terminal and append --output file.extension to save the content in file.extension since terminal isn't capable of showing binary data.

An example of the command:

curl 'https://company-my.sharepoint.com/personal/path/_layouts/15/download.aspx?SourceUrl=
%2Fpersonal%2Fsome%5Fpath%5Fin%2Ffile' -H 'User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux 
x86_64; rv:73.0) Gecko/20100101 Firefox/73.0' -H 'Accept: text/html,application/xhtml+xml,
application/xml;q=0.9,image/webp,*/*;q=0.8' -H 'Accept-Language: en-US,en;q=0.5' 
--compressed -H 'DNT: 1' -H 'Connection: keep-alive' -H 'Referer: https://company-my
.sharepoint.com/personal/path/_layouts/15/onedrive.aspx?id=%2Fpersonal%2Fagain%5Fa%5Fpath%2F
file&parent=%2Fpersonal%2Fpath%5Fagain%5Fin%2&originalPath=somegibberishpath' -H 
'Cookie: MicrosoftApplicationsTelemetryDeviceId=someid; 
MicrosoftApplicationsTelemetryFirstLaunchTime=somevalue; 
rtFa=rootFederationAuthenticationCookie; FedAuth=againACookie; CCSInfo=gibberishText; 
FeatureOverrides_enableFeatures=; FeatureOverrides_disableFeatures=' -H 
'Upgrade-Insecure-Requests: 1' -H 'If-None-Match: "{some value},2"' -H 'TE: Trailers' 
--output file.extension

Further Reading: why would curl and wget result in a 403 forbidden?

In order to solve it, I've just gone through the following two steps.

1. Change scope to drive - as suggested here and here.

   SCOPES = ['https://www.googleapis.com/auth/drive']
   

2. Delete token.pickle and run the script again - as suggested here.

Then, manage to download the file and it works fine.