Because Manager is an accounting system (not a CMS, booking system, CRM, etc) there are certain features that it does not have, and is not likely to ever have. My guess is that this falls into that category.
Your best bet would be to build a custom solution for your booking needs and connect it to the Manager API, or find an “off-the-shelf” (pre-existing) solution that also has API access and connect that to Manager. Both options would likely require hiring a local professional if you do not have the technical knowledge yourself.
@ShaneAU’s comment from 9 months ago is still valid. Since then, there have been many new accounting features added. But no move towards resource scheduling or personal calendar capabilities. There are too many established apps on the market for things like that to think that Manager, as an accounting program, will move in that direction.