SMS off MacBook Pro

Had the same problem. No clue why Apple decided to change all this without letting anyone know, however, I fixed this by doing the following. See the writing I put in BOLD:

• On iPhone, go to Settings > Messages > Send & Receive. Make sure that the Apple ID at the top of the screen is the same Apple ID that you're using for iMessage on your other devices. Add a check to your phone number and email address, so that you can be reached by iMessage at both. Do the same on your iPad or iPod touch.
• On iPhone, go to Settings > Messages > Text Message Forwarding, then choose which devices to allow to send and receive text messages from this iPhone. If you're not using two-factor authentication for your Apple ID, a verification code appears on each of your other devices: enter that code on your iPhone.
• On Mac, open Messages, then choose Messages > Preferences. Click Accounts, then select your iMessage account. Make sure that the Apple ID shown here is the same Apple ID that you're using on your other devices. Add a check to your phone number and email address.

A Mac has no capability whatsoever to send or receive SMS cellular text messages. A Mac does not interact directly with a cellular carrier.

A Mac may use an iPhone in a Continuity sense, however, to access an SMS capability. See "SMS and MMS" here.

Use Continuity to connect your Mac, iPhone, iPad, iPod touch, and Apple Watch - Apple Support