Encryption: decrypt files recovered from an encrypted external hard drive

I am trying to recover data from one of the external hard drives of my company. I ended up using DiskDrill to extract all the files on a new, unencrypted hard drive. Unfortunately, I made the mistake of erasing the original hard drive before correctly checking the exported data …: /

If I look at the recovered data, all the file structures and file sizes look correct. But if I try to open any file, a system error appears that says:

"The document" File.rtf "could not be opened."

I used cat to verify the contents of the file, and because of the result, it seems to me that it is still encrypted:

|?!? z? n; AԒ ?? Ћ ??? f ?? Y? -? BA? – ?? W? 5? vc? D ??? yr ???? l? & yg ???? ? OR #
????Florida??
?? = ?? S ????? # t ???? v: ?? #? ˰wDZ $ ?? and>? N ?? Y ?? C? J ??, ??? WI? L?[?a??CC?
P?U?>K?l?Ե???????OH?[Ẉ[Y?’^k?*?mDћ)?,0?Ի;
??^?dW?|?`??=?c6&-~??YT+3w?4d?’?F@???D???G(?$??>??+?҃?6?t????p?M?wC[?:?$d1?{?Ϊ?.???~KW?r??Q?6??
o@???u???
?B|?[[??>/%???$??[;?z?h?!???O??dn??;?”?GZ?v?{W?B???[???P?d?!????d??Q?@?mG??/?|?x?_???H%)?v?Z??$?]???? F ??>? "????! U? RFl ???
? GB2? HOW?]?? | x ??]X ?? aN[??????WJ??????lB??噡g?ہ'I???^}Yk>??Ǘ[??????WJ??????lB??噡g?ہ'I???^}Yk>??Ǘ[??????WJ??????lB??噡g?ہ'I???^}Yk>??Ǘ[??????WJ??????lB??噡g?ہ’I???^}Yk>??Ǘ

The command:

File - /Users/Cortana/Desktop/File.rtf

Returns:

application / octet-stream; set of characters = binary

The original disk was formatted using FileVault. I know the original password.

Is there any command I can execute on the terminal (or anything else really) that I can do to recover my data? I'm not a Unix expert, please explain it to me as if I had 5.

Thank you,
Danny