One of the websites I maintain has 50GB storage but the website uses under 100MB and will not increase in size significantly. Would there be any problem isn using 10GB for independent cloud storage for file, documents etc.? I can see no problems but would like to check first.
You don't specify what problems you envisage, so I will assume you are not asking whether it is a technical issue, rather whether you are allowed.
It will 100% depend on the terms and conditions of your host.