Restricted list of add-ons

[Barrie McGuire]

I've just created a bitbucket free-tier account, hosted by Atlassian.  I'm trying to add a specific add-on:

https://marketplace.atlassian.com/apps/1211854/yet-another-commit-checker?hosting=datacenter&tab=installation

However none of the documentation I can find online seems to be accurate, I don't have the ability to search for custom marketplace add-ons, or to upload jar files.  I can only select from a predefined list (see attachment). 

Not sure what to do? Is this a limitation of free tier?

Thanks