The Developer tab isn't currently a feature of PowerPoint 2016 for Mac or PowerPoint 2019 for Mac. You can vote for this feature by going to the PowerPoint for Mac suggestion box about this subject and clicking the vote button. This helps us prioritize new features in future updates.
While there is Developer tab, the features you want still exist:
Editor Choose the Tools > Macro > Visual Basic Editor option
Macros Choose the Tools > Macro > Macros option
Add-Ins Choose the Tools > Add-Ins option
PowerPoint expert Geetesh Bajaj has written about macro and developer tools on his site, indezine.com: Missing Developer Tab of the Ribbon in PowerPoint for Mac