"In the platform" or "on the platform"?
I don't mean such platforms as Netflix, Youtube or social media platforms. If this is a marketing automation platform (in other words - software), can we say "in the platform"?
In the HubSpot Marketing Automation platform, you can set up such automation workflows as a welcome email, abandoned cart emails or onboarding workflow.
Solution 1:
I think this specific use of platform (an application or website that serves as a base from which a service is provided) is quite new, so the "preferred" preposition usage hasn't exactly settled down yet. It's by extension from the already metaphoric sense a means or opportunity to communicate ideas or information to a group of people (alluding to someone standing ON a raised platform to address a crowd), but arguably the "container metaphor" allusion (IN) suits the modern meaning better.
Semantically speaking, the specified context involves actually working in an environment, rather than on a "platform". And it's worth pointing out that when the OP was simply trying to present an "example" context in two comments, they quite naturally wrote In the HubSpot Marketing Automation [platform] you can [do things] when all they wanted to do was communicate (without thinking about the "grammar" as such).
TL;DR
This is a stylistic choice, not a matter of grammatical rules. But my choice would always be for in here, because semantically speaking, the metaphoric usage refers to a working environment (container metaphor) rather than a position of high visibility for addressing a wider audience ([raised] surface metaphor).
Solution 2:
Personally as a Software Engineer I use it like this:
ON the platform, when I am actually using the platform.
Example: "I am on the marketing platform right now looking at data"
IN the platform, when I am "inside" of the platform and change things programatically or change settings etc.
Example: "I am in the marketing platform changing parameters"
Hope that makes somewhat sense?
Solution 3:
In the platform is less common than on the platform, and in most of the examples found with in, platform is an attributive noun:
in the Platform Era; in the platform economy; in the platform society (Googlesearch)
So, although the GNgram comparison between the two is not accurate, it does point to the fact that in the platform is still rare.
There is a particular instance where you can use in the platform in the way you suggest, when there are technical changes done in the structure or system of that platform.
On the platform suggests that it is up and running and something occurs on it, as we say that something occurs online. When you do something on a site, we assume that the site has been set up and functioning, and you use the services/functions it offers. To change something in its structure as a developer, would rather be described by the preposition in.
Your sentence is an instance of a technical change in the platform, so I would definitely go and use it:
In the HubSpot Marketing Automation platform, you can set up such automation workflows as a welcome email, abandoned cart emails or onboarding workflow.
You set up an automation in the platform, it is a change in its functions, in its structure, so that people can use these functions while they are active on the platform.
However, as showed in the comments, the use of in is starting to overlap with that of on with "platform", as the concept of virtual space is becoming more solid.
Solution 4:
Of those two, on the platform is more correct (especially when referring to a physical platform).
In context, however, that word choice is better avoided entirely with something like using the platform instead.