I am coming to terms with the Web Forms Identity template and when I try to compile my Web Forms project in VS 2017, I get the following: error ASPCONFIG in my Web.config(18) file:

'It is an error to use a section registered as allowDefinition='MachineToApplication' beyond application level. This error can be caused by a virtual directory not being configured as an application in IIS'.

I see no reference to allowDefinition or MachineToApplícation in the entire Solution - let alone Web.config - when I search for either of those terms. This is line 18 in my Web.config file:

<authentication mode="None"/>
There seems to be two servers that my project uses which I can see in SQL Server Object Explorer:

(localdb)\MSSQLLocalDB (SQL Server 13.0.4001)
(localdb)\ProjectsV13 (SQL Server 13.0.4001)

If I need to configure a virtual directory as an application in IIS, how would I do that and which directory?!

It's all a bit beyond me, but thank you for any help.