Yes, this can be properly used without charges through a free accounts however the services are very limited. If you wish to enjoy cloud-storage and exactly what Fileboom has to offer, it is highly suggested that you upgrade to a premium accounts.
First, you have to register first and then upgrade your account to a superior one. Opt for the top plan you wish to avail and also pay for it all through the available payment methods (Visa, Mastercard, American Express, Bitcoin, Paypal, JCB, Discover). When payment is successful, your account will be instantly upgraded to a premium version.