I tried loading Dorico just now but I cannot open it and when I input the installation code I get the following message.
Help please “The activation code has been used already. An activation code can be used only once to download or upgrade a license. Please contact your software vendor to get a valid activation code.”
It sounds as if you have maybe installed Dorico on a new computer? If so, please follow the “Reactivation” workflow as described here.