You create the “ web instance” variable.
So, for practice, do a Launch Chrome command, to a website with a login. In that command, you declare the variable for web instance. By default it is %Browser%. Now use the web recorder to enter the username and password. When you are done, you can see the web actions in your flow, and they will all reference the %Browser% variable. This variable is the web instance. So, if you are getting an error that “the web instance cannot be found”, it is because the web instance in the command that errored out does not match the web instance declared in the “Launch Chrome” command.