A private key can be encoded in a number of different formats:
- 51 characters base58, starts with a '5'
- 64 characters [0-9A-F] hexadecimal format,
- 44 characters base64,
- 52 characters base58, WIF Compressed, starts with a 'K' or 'L',
A bitcoin address, which is a hash of the public key, is 25-34 characters, typically 34 characters,
Maybe a bitcoin address could be encoded in some other format, but 25-34 characters of base58 is the standard.
I don't know what kind of validations are in place at bitbrothersllc, but they should easily be able to see that you entered 51, 64, 44, or 52 characters instead of the 25-34 characters that would make up a valid bitcoin address.
Contact them. If they are legit, you'll get your funds back. Good luck!