Simply open your edit Account settings page (Settings >> Account >> edit or click here) and scroll down to the Social Links section:

Multi-Business account. You can add a WhatsApp link for each of your Businesses in the Companies list. Select a company, click edit (top right corner), and scroll down to the Social Links section.

Your WhatsApp Link will appear in the Company Information section, next to your Social Links.

You can create a link to start a WhatsApp chat by entering your number at the end of the following link:

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.

Examples:

Correct: https://wa.me/1XXXXXXXXXX

Incorrect: https://wa.me/+001-(XXX)XXXXXXX

You can learn more here >>>

If you have a WhatsApp Business account, click here, to find out more about getting a link to your WhatsApp Business Channel.