you'll need to be connected, at least, episodically (eg, monthly for monthly subscription) to, at least, sign in. so, if by bad connection you mean you don't have a connection, you won't be able to use cc.
if you mean you have trouble downloading large files, you can usually work around that issue.
you don't have to use the cc desktop app, but you'll still need to download the installation files or have someone else download and transfer them to you (eg, using a usb stick).
you don't have access to free wifi anywhere nearby?