You can use the Axsy Smart Forms Web UI to import a form JSON into an Org via Salesforce Web. This import will deal with the automatic creation of Form Elements that are included in the form itself.

Steps to Import a Form

Once you have retrieved the Form JSON, log into Salesforce Web in the Target Org. Navigate to 'Axsy Smart Forms' from the 9-dot App Launcher in the top left corner, and click the 'Form Import' tab (see Figure 1)

Figure 1 - Form Import Location

Once in the 'Form Import' tab, you can drag and drop a file or click 'Pick a File' which will bring you to your file explorer where you can select an individual JSON to import.

Before saving the Form you will be met with a 'Summary' screen (Figure 2). Here you can see all the sections of the forms, as well as their individual element name and type. Additionally, there is a 'Details' tab (Figure 3) where you can inspect the form json at a more fine-grained level.

Figure 2 - Imported Form Summary

Figure 3 - Imported Form Details

Once the Form has been reviewed via 'Details' or 'Summary', the Form can be cleared or saved.
If cleared, no data is committed to the org. If saved, the new Form will appear under the Forms list.

Note: Depending on the type of Form Elements within the Form, the Form Import may faily - you can check whether the Form Element Type is supported by checking the settings for Form Element in Object Manager, and adding the new type name (e.g. Assessment Indicator Definition) under values for the Type Picklist

Steps to Download a Form JSON

In addition to the method listed here, Forms can be downloaded via the Form Designer. 
Once a Form has been opened you can click the download button highlighted in Figure 4, which will download the Form JSON to your device.

Figure 4 - Download Form JSON Button