This means :- sonarqube don't have any info about your project. you need to setup your project in sonarqube.
The end goal here is to get your login - which is a guid for example, "9f6cf20347297da17ce4591b1d2ada820a30d23e" and your project key which is a unique alphanumeric value to differentiate your project.
Goto Create Project - > Generate a token -> Provide your project name -> Select C# or VB or Java (when prompt Run analysis on your project"
At the end of the dialog you will get Login :- which is a has and Project Key.
Then you pass those info into MsBuild or whatever build tools you currently using.