DisCloud MND is a web application developed by unknown developer to simplify file sharing between your main computer and another computer that you may not fully trust.
Logging into Google Drive on an untrusted computer could be risky if it has a keylogger or if you forget to log out.
Files sent to DisCloud are not meant to be highly important, so unauthorized access to your DisCloud account should not be a major concern.
Additionally, the login key is managed through your Discord account, meaning that an attacker would need access to your Discord account to cause any damage.
However, you are not required to log into Discord to access your DisCloud files.
For security reasons, never use your Discord account password as your DisCloud login key!
Doing so would completely defeat the purpose of this application's security design.