SVN to Git migration with Gitlab SaaS tier

I work on a team that has projects in Subversion and we would like to migrate the repositories to Gitlab. We need to maintain all history from Subversion projects. The issue I am running into is that our team uses the free tier of Gitlab SaaS. So, as far as I can tell, we have no access to the central Git server?

Following the docs for SubGit (Migrating from SVN to GitLab | GitLab) it appears that access to the Git server is required. We would like to set up mirroring to avoid having to a hard cut-over to Gitlab all at once. We would much prefer a smooth transition that can occur over a period of time. As far as I can tell, there is no way to achieve this with our current Gitlab subscription. Am I missing something?

I do not claim to be a Git or Gitlab expert, so hopefully there is a simple solution that I am not seeing.