At first, I used the default Client ID, but then I read that it's better to have your own and I think that I managed to set it up correctly. I'm not 100% sure, because the instructions are a little outdated in the sense that Google renamed/changed things around. However, I set up the client ID etc. and input the data into rclone, and it works, except that it didn't affect the upload speed in the least. I think that if I set it up wrong, then it wouldn't work at all.
[deleted] I have AirVPN, but obviously I turned it off for the test.
100 Mbps is per ISP specification. Currently, depending on speedtest, I get 100-120 Mbps.