To install your signature on Windows 10 Mail:
Open your signature in Chrome
Select the signature in copy it to your clipboard or for better results, click on the open in new tab button then select signature and copy to your clipboard
Open the Windows 10 Mail app
Click on the settings icon on the bottom left of the app
Click on the signature link on the right side panel
On the signature window that shows up, right click on the editor and click on the little arrow next to the paste link
On the expanded menu, select the "Keep Source Formatting" option and you are done
That is it, now your signature is installed and ready to be used in Windows 10 Mail