You can access Submitted Forms through the Web Portal and the App.
Custom submitted tabs are also available based on Group visibility when creating the tab/s. Tabs can only be created in the Web Portal when in the Submitted Forms list.
In the Web Portal go to Forms > Forms Dashboard > Submitted Forms.
Or go to Forms > Submitted Forms.
To see forms connected to a specific client, in the web Portal go to CRM > Contacts > Select Edit arrow for the Client > Activity > Forms.
In the App, go to Forms > Submitted Tab > Search for the Form to open it (you can search via the custom submitted form tabs, just below the search bar).