issue with updating software on ipad mini 5

Hi all, just purchased a ipad mini (5) and want to update the current software (13.3.1) and would like to get the 15.0 version. When trying to update the software, receive the following message "unable to check for update...an error occured while checking for a software update". I tried itunes, did not work. Do not know how to fix this concern. Thanks for your support.