Do I need to go pro?

Hi guys - only just joined roll 20 today on a free login and very interested in using isometric assets. All of the ones I have seen are recommending their map size in units rather than pixels - having a free account I don’t seem to have this option - I’ve only seen mention of changing map size to units  using scripts... do I need to go pro to unlock this as an option... it’s not the money, just want to get my head around things before I sign up

No, you don't need to go pro for this. I'm on mobile at the moment so I can't provide a screenshot, but a unit is a Roll20 unit of measurement. It's essentially 1 square, which defaults to 70px. When you choose to resize an asset in the vtt, you can right click it and select "set dimensions". This dialog has a drop down to set the dimensions in either units or pixels. Setting by units will respect the current page's square size.

Thanks for your help