A 19.9 MB text file is unusually large for just 200 accounts. A standard list of 200 usernames and passwords would typically be less than 50 KB. A file of this size suggests one of three things:
The search term "exclusive download 200 steam accountstxt 19907 kb" exclusive download 200 steam accountstxt 19907 kb
Using such credentials to access someone else’s Steam account is and theft in most jurisdictions (CFAA in the U.S., Computer Misuse Act in the UK, etc.). Computer Misuse Act in the UK