Power BI Bubble Map using offline map

Hi. I have Power BI Desktop in 2 environments - 1 completely offline due to data sensitivity (Virtual Machine), the other local laptop has internet access

I'm hoping to create a bubble map to represent relative numbers of admissions to Victorian hospitals

I can do this in the local environment with internet access, but not sure how to provide the back end map data in the offline environment. I've previously created and uploaded Topojson files for heatmaps to the virtual machine, but can't use them with the bubble map type in Power BI (no option in the format tab)

Grateful for advice