I hate to have to say this but it is very unlikely that you will find any free file storage services that use FTP. And if you find anything free that uses FTP, it's likely not going to be for the purposes of file storage, and will state so in their TOS. You will probably only find some free (and rather unreliable) web hosting services in which their storage space is specifically for storing your website's files and using it for anything else will likely get your files deleted.
But you are not stuck with Google Drive and their software that doesn't seem to agree with your pc.
There are others, and their software may be more agreeable.
Here are the ones I have tried that seem to work ok for me (YMMV)...
1. You can try Dropbox
, which gives you 2GB free to start, 2.5 if you use my referral link
. This is the one I like the best for a lot of reasons...including using it with a WP plugin to make automatic weekly backups of your website's database and files and storing them offsite on both Dropbox and an external drive connected to my PC.
2. You can try CX
, which offers a personal Starter plan that is essentially the same as their 10GB Starter Plus plan, except that it's free, and you have to login at least once every 15 days to keep it activated. You can use my referral link
to get an extra 300MB of space.
3. Or you can try SugarSync
, which has a free plan that gives you 5GB free to start with, 5.5 if you use my referral link
. One thing I do not like about this one is that it doesn't support external drives. I pretty much only use this one to store downloadable files for certain websites of mine in which I do not have storage options for anything other than images, with the web host. (Sharing the links to the files on SugarSync does give me some basic download stats, which is something I do not get if I share Dropbox links.)
All of these require you to install their software, which does autosync files. But none of them require you to run the software at all times. You can sync and exit. The only one I keep running at all times is Dropbox.