you have an address that you want to check, each address (based on its type) corresponds to a certain type of script in this example the address starting with 1 is a P2PKH address so the script of it is DUP HASH160 <hash> EQUALVERIFY CHECKSIG
so you start from the address:
1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa
base58decodecheck to get the hash (after removing the version byte)
62e907b15cbf27d5425399ebf6f0fb50ebb88f18
build the script from the hash
76a914
62e907b15cbf27d5425399ebf6f0fb50ebb88f1888ac
now you hash it using the hash you specified for the server (it is apparently SHA256 by default)
SHA256('76a91462e907b15cbf27d5425399ebf6f0fb50ebb88f1888ac') =
6191c3b590bfcfa0475e877c302da1e323497acf3b42c08d8fa28e364edf018b
but the document says that for sending this hash digest to the server you must reverse its endianness so you simply reverse your bytes that you get from the hash result then send it to the server. the reverse of the hash is:
8b01df4e368ea28f8dc0423bcf7a4923e3a12d307c875e47a0cfbf90b5c39161
(note the start of previous code block with the end of this last code block: 0x61, 0x91,... turns into ...., 0x91, 0x61