I have a problem when using a free template and making the home page a static page, it appears in the webmaster that I have a page that is not compatible with mobile devices, what is the reason for this is my site please help
Welcome to the forums, @arbdareg.
What do you mean by that? Are you seeing the message in Google Search Console?
Have you tried testing the page with https://search.google.com/test/mobile-friendly to get more information?
It sounds like it may be a very old template that was not designed to cater for mobile devices.
If so you should probably choose a different one for your site.