Procreate is doing very well, today it was the 37th top US grossing app in the App Store. I would like to receive alerts when a Procreate question comes up, and as far as I can tell will need it to have a tag, to do so.
I added a procreate tag to your question. You should be able to use it now.
When proposing new tags, please also propose texts for the tag descriptions so the community can improve on those to have a common understanding.
Having said that: tags should be used to add value to a question by providing additional categorization/grouping. Any question about Procreate will already have the application name in the question somewhere, so also having a tag doesn't provide a lot of value. Also, we currently have exactly two questions mentioning Procreate, and the older one isn't actually about Procreate as such. So I doubt that there really is a need for a new tag on this currently.