A message pops up saying you need to upgrade your subscription in order to create new templates, but you are sure you have not reached your limit yet?
If that is the case, the following could be happening:
You have more than one business under the same account.
Remember that all templates you have created for your different businesses count towards the total allowed per account (3, 10, 25, or more depending on your subscription).
You have archived templates.
Archived templates will count towards the maximum total allowed per account.
In order to add a new template, you will need first to delete some of your unused/archived templates to free up the quota.