Adding logos in footer section

It’s correct, but you might need to adjust the CSS as well:

.custom-footer-image {
    display: flex;
    justify-content: center;
    align-items: center; 
    gap: 1rem;
    
    a {
        max-width: 30%;
        height: 100%;
    }
}

Make sure to use https as stated Lilly and change the two first links:

<div class="custom-footer-image">
    <a href="https://" target="_blank">
        <img src="https://cdck-file-uploads-europe1.s3.dualstack.eu-west-1.amazonaws.com/standard21/uploads/fspm/original/1X/f2f2e6d11a09f6ceadecf437c48b24c8f44ea76d.png" alt="Footer Image" />
    </a>

    <a href="https://" target="_blank">
        <img src="https://cdck-file-uploads-europe1.s3.dualstack.eu-west-1.amazonaws.com/standard21/uploads/fspm/original/1X/0da449a3a30e30eaa4467e96189b7bd4e0a28a64.png" alt="Footer Image" />
    </a>
    
    <a href="https://algorithmicbotany.org/" target="_blank">
        <img src="https://cdck-file-uploads-europe1.s3.dualstack.eu-west-1.amazonaws.com/standard21/uploads/fspm/original/1X/27ca1fc832ecd29153d2ff150011e0dc056d4f93.png" alt="Footer Image" />
    </a>
</div>