For most of the globe agriculture was not possible. While canines were probably domesticated in the glacial period, they served as hunting partners primarily. It's actually quite hard to build fencing over large amounts of land area (like sheep and cows require) that is capable of keeping animals in, unless you have metal to cut wood with. The United States had open cattle ranging until barbed wire was invented in the 1870s, since it was too difficult to fence. And open ranging was only possible after horse domestication.

We also do not see evidence of grain domestication or any kind of real farming until the start of the Holocene 10K-12K years ago. The climate was not particularly friendly to farming, and without access to metal, farming is orders of magnitude more difficult.

The original article is about Australia alone, and 45K years ago, Australia probably had a human population in the low thousands, with it being on the frontier of human expansion at the time. There is no evidence of massive human population at that time or any time before 12K years ago. In fact, there's several population bottlenecks where they think the total number of humans alive globally was around a few thousand.

https://pubmed.ncbi.nlm.nih.gov/9650103/

https://pubmed.ncbi.nlm.nih.gov/18922561/