If you are receiving a 404 error, please resave or update your permalinks. Sometimes when a new plugin is installed or updated, WordPress can lose the permalink settings for the plugin. This can be accomplished by going to Settings > Permalink Settings and just resaving the permalinks. You do not have to edit the permalinks unless you want to. Just resave them and the 404 error should go away.
If that does not work, please ensure you have added shortcodes in the Shortcodes section because the contract will not work without shortcodes being added and completed when the contract is created. Add your shortcodes and fill out the contract in the Add New or Edit contract window.