You can generate current date and time using “Create Date&Time Range” node. There is an option in its configuration window below start and end points for this (“use execution date&time”). After creating the date, use a “String Manipulation” node to generate the path including file name, for example: join("C:\\Daily Report ", string($Date&Time$)). Then use a “Table Row To Variable” node to generate a flow variable which contains the path and the file name created in the previous step. Now feed the flow variable to the “Excel Writer (XLS)” node and in the configuration window of the node, for the output location, beside the “browse…” button, you can see another button which is to use flow variables for that setting. Click on it and use the variable you’ve created as the path. Done!
This is likely because you haven’t created a path variable upstream that is connected to the writer node (I’m making an assumption here since you are only showing screenshots of the configuration window, and not the workflow itself). You also need to connect a table to the input port of the node.
If a path variable already exists, it should be available for you to choose: