2. Enter a name for your template in the textbox and press the button “Create Template”.
If you set the checkbox in the "Allow External Sharing"-Field, the external sharing setting will be automatically set in the External Access Settings. 
For more informations please read External Access.

3. The Collaboration Manager 365 App creates a new template asynchronous. This can take several minutes. Just wait until the templates library has a new entry.

4. To edit the template click the url. Then modify the site template with SharePoint Standard features.

5. After you have finished modifying the template navigate back to the template library and select the template. Select the “FILES” tab in the ribbon bar and press the button “Save Template”.

6. Please wait until the template is successfully saved. Check the modified field for a newer modified date. (Actually there is no status field).