Commercial property investment is GST applicable

I was wondering if someone could advise me on this situation.
I have invested in commercial property space. The property pays a monthly commitment charge at a fixed rate. This investment is in a different state than my residence.
Now they are asking me to register for GST and start raising invoices every month.
My question is:
Is this correct and this investment is liable for GST?
If yes then who is liable to pay this tax, me or the property company?
When raising this invoice monthly do I add the portion of GST to the commitment charge?
Can someone point me to the portal to register and then explain the process of paying the tax collected by me online every month?

I will be extremely grateful if an expert can respond. I am even willing to have offline discussion to clarify my situation.