How to open folder indexing in robots.txt?

Question

Search Engine Optimization

The site has a Russian and English version
In the clone of the ru page
In the en/ folder there is no page in English
There is no engine, just html +

css

User-agent: *
Disallow: 
Host: sitet.com
Sitemap: https://site/sitemap.xml

Answer 1

tested the folder of the English part of smite and gave out such a picture

Answer 2

specify what exactly you want to allow and what to prohibit.
now there is an error in the code:
Disallow:
after the colon, you should indicate what exactly is closed from
host indexing - an obsolete directive, not supported.
it's not a bug, it's just not needed

Answer 3

To index everything:

User-agent: *
Allow: /