First up, you need to create the link for "WhatsApp Click to Chat" functionality. Here is how you can do this:
Create your own link
Use https://wa.me/<number> where the <number> is a full phone number in international format. Omit any zeroes, brackets, or dashes when adding the phone number in international format.
Don't use: https://wa.me/+001-(XXX)XXXXXXX
Create your own link with a pre-filled message
The pre-filled message will automatically appear in the text field of a chat. Use https://wa.me/whatsappphonenumber?text=urlencodedtext where whatsappphonenumber is a full phone number in international format and urlencodedtext is the URL-encoded pre-filled message.
Once you have created the "Click to Chat" link, you will have to create a QR code so that your customers can scan it and open your WhatsApp Chatbot. Here is how you can do this:
Paste the "Click to Chat" URL
Download the generated QR code image