Announced: 04 Oct 2017; Construction Start: 04 May 2019. Timeline matches then I think.

260 Qatari Riyal = 72 USD. Imagine what it’d cost if the victims’ families were properly compensated:

Wiki - Qatar

Also a comment from March on Theme Park Investigator:

The park will never fully open, since the main contractor did not pay the suppliers. All are refusing to return to finish their works. It’s a shame as it would have been an amazing park.

Then there are photos from May alleging various rides are not open.