This was sort of answered on this thread:

https://www.odoo.com/forum/help-1/question/export-setting-and-data-from-odoo-com-to-local-odoo-server-installation-54962

Seems logical that you would jsut backup then restore locally but there may be pitfalls to watch out for.  Certainly, it would probably be a good idea to match installed modules and versions of the software between the online and local installations.

If you ahve a fresh local installation then you can try it and see how it goes.  Please do report your success or failure back on this forum because I am sure that many (including me) will want to know your results.  Thanks.