It looks like you selected the option but didn't paste the file name. Could you please share:

1. The file name - something like google1234567890abcdef.html
2. The content inside the file - usually a single line like google-site-verification: google1234567890abcdef.html

You can find both in Google Search Console under Settings > Ownership verification > HTML file. Google will show you the file to download - just share the name and content and I'll add it to your site.