To add Aave to your Metamask wallet, you can follow these steps:

Open your Metamask wallet by clicking on the extension icon in your browser.

If you already have an Ethereum wallet set up, click on the three dots in the top-right corner and select "Add Token."

Click on the "Custom Token" tab at the top of the page.

In the "Token Contract Address" field, copy and paste the Aave token contract address: 0x7Fc66500c84A76Ad7e9c93437bFc5Ac33E2DDaE9.

The "Token Symbol" field should automatically fill in as "AAVE." If it doesn't, enter "AAVE" manually.

The "Decimals of Precision" field should automatically fill in as "18." If it doesn't, enter "18" manually.

Click "Next," review the token details, and then click "Add Tokens."

You should now see Aave in your Metamask wallet along with your other Ethereum-based tokens. If you have any Aave in your wallet, you should also see your balance. You can use your Aave tokens just like any other token in your Metamask wallet, such as sending them to another wallet or using them to pay for transactions on the Ethereum network.

In metamask you have the add token button too, you can search in the list for AAVE and LINK, both appear there (Ethereum network ones)

Or

Follow this guide : https://revolutionaryspaces.medium.com/when-your-transaction-fails-on-polygon-390e123ae624"