If this happens, please do not worry! Ascendant PRO and Ascendant Lite are child themes of Allegiant PRO and Lite, which means that they need to have Allegiant installed in order to work.
If you purchased Ascendant PRO, you should have received zip files with both themes.
When you go to your account you should find there both themes. Download them from there and then go to your website’s dashboard > Appearance > Themes > Add new > Upload > and upload the zip file with Allegiant PRO first > Install and activate it and then do the same for Ascendant: install and activate it.