I’ve set my litecoin public key correctly but it’s not giving correct wallet address on payment link.
Hi int1516,
Welcome to the forum. Our system generates addresses using the m/84’/0’/0’ (P2WPKH) derivation scheme, which is used by most modern wallets. However, not all wallets use the same derivation scheme. Could you share which wallet you are using?
Hi, I’m using Tangem wallet How to Get the Xpub (Extended Public Key) in Tangem Wallet | Tangem Blog
According to this article, Tandem Wallet supports both, the Legacy (P2WSH) and the Native Segwit (P2WPKH) derivation schemes. There must be a switch somewhere that tells it which one to use. You can also try asking them directly how to generate m/84’/0’/0’ addresses.
I found how to generate m/84’/0’/0’ address saved the new xpub at atlos dashboard but still payments generate invalid ltc addresses 
I suspect that the wallet you are using is not really using the m/84’/0’/0’ derivation scheme. Usually, these public keys should begin with “zpub…” We can try isolating the issue. Try, just for an experiment, using Electrum Litecoin wallet to see if the addresses will match.