I think they’re working on letting you specify the download location for the Marketplace content, but after downloading, if you move the content to another drive I don’t think there should be any problems with running the project file, have you tried that?
Have you let the launcher update yet? Because if you did, it’s already there, right before you hit the download button, you can select a different download path at the bottom of the page.
Didn’t spot that, pretty good that they’ve already implemented it. Having to click the path in order to change the download location isn’t ideal from a UX standpoint though, it might be better if it asks you as you’re downloading where you want it do be placed.