How can I earn additional 100G? not 2TB I don't need 2TB, it is too big for me, so can't use it all. I just need 100G, and it would be enough for me.
Dropbox doesn't have a plan smaller than 2TB. You can earn an additional 16GB through referrals, and some mobile devices and computers include between 20 and 100GB of storage for a limited time, but that's it.