4.7.29 not installing on test site
First, CiviCRM is always available freely, and never for sale. You shouldn't be purchasing CiviCRM from anyone (CiviCRM installations are different). It's free to download, use, and install yourself, without limitations. If anyone is trying to charge you for a CiviCRM license, please take them to court for fraud by misrepresentation.

At which stage are you getting this? Which tables have been created in the DB?