You can install the Mercado Pago extension at no cost through the Adobe Commerce store, it's very simple. Follow these steps:

1. Access the Official Adobe Commerce Store. In the search engine, type Mercado Pago and select the official extension.
2. Open the Edition menu and select the module edition you require. Then open the Your store version menu and select the type of version you need for your business. Finally, click on Add to cart to add the module to the cart.
3. Click on the cart at the top right of the site and then click on Proceed to Checkout to finalize your purchase.
4. To continue, you will need to login with your Adobe Commerce account or create a new one. Once registered, you can download the Mercado Pago module and install it.
5. Then, follow the instructions from the documentation for Installation via Composer.