Check the statlines for the units in the book. If their WS and BS are values like "3+" then it's the correct edition. If the values are like "3" or "4" without a "+", then you have an old edition.
In addition to Codex: Craftworlds, you'll need the latest Chapter Approved book, which includes GW's balance changes to points values. The most recent Chapter Approved book is Chapter Approved 2019, which was released in December on 2019.
There are also optional supplementary rules available in Psychic Awakening: Phoenix Rising. These focus on Craftworlds and are pretty strong. Might be worth picking up, particularly for the new spell lists.
There are some other supplementary rules in Imperium Nihilus: Vigilus Defiant, but it doesn't particularly focus on Craftworlds, we just get a bone thrown our way. You can and probably should skip this one.