You need to choose which cryptocurrency you want to purchase and find a stable version of the wallet.
As a rule, each cryptocurrency has an official wallet client.
Please note that each wallet has its own unique address or private key tag, which is required to restore your wallet if access to it is lost.
It is important to keep in mind that the crypto exchange never asks for your private keys.
Keep them in a safe place and do not show them to anyone.
If the secret keys are stolen, your wallet with all cryptocurrency will be lost forever.