Purpose of this script is to allow vTM to manage certificates with the Let's Encrypt Certificate authorities. letsencrypt.sh needs a third party script to handle the connection with Let's Encrypt. We use https://acme.sh for this purpose.
For installation instructions, please follow up this blog post on Brocade Community website:
Please note that native support of Let's Encrypt in vTM is in the Roadmap. Once done, this script will become obsolete.