There is no limit on the total number of files that you can post to CoConstruct. However, you will be limited to a total of 20 files and/or 75MB size per upload.
If you're on an older plan, there may be a restriction on the total storage capacity for your specific account. If you find that you need more space, contact your CoConstruct representative or send an e-mail to support@coonstruct.com, or through one of the ‘Contact Support’ links in the site, for help.