Can't send raw transaction Bitcoin Core 0.19.1 - non-mandatory-script-verify-flag (Signature must be zero for failed CHECK(MULTI)SIG operation)
That error message is irrelevant.
SegWit introduced a new way of producing the hash digest for signing which requires the "amount" being spent to be included during hashing. This "amount" is the value of the output that is being spent not the amount of the new output you create. In your it is 0.02641617 or the actual value 2641617 in satoshi.
Your step 4 should become:  

signrawtransactionwithkey '0200000001ffab477941a9eba13b89bd815947a4c1daccc3a42dfb090c1006479eee1fe78e0000000000ffffffff0180841e000000000017a914d0c3f50336b5f109207d722c692191ff86263e968700000000' '[" $privKey "]' '[{"txid":"8ee71fee9e4706100c09fb2da4c3ccdac1a4475981bd893ba1eba9417947abff","vout":0,"scriptPubKey":"a91429c3d920cd18e34db9035c4322474aae4465792187","redeemScript":"00143b88811e01b3efaa0bcd9da16ef85ef3a1583349","amount":0.02641617}]'