Here my 5 cents!
I passed the Activate12 certification using the content of Activate05 from erprep. There is a range of 50-60% of similar questions in the test, so, pay special attention to S4 Hana Cloud STE topic, Transition path "selective Data transition' and memorize accelerators per phase/workstreams. I found very easy the Agile section (read the act200). The passmark for Activate 12 is 61% compared to Activate 05 68%, so, i suggest to take the latest version, it's achievable.
Defitively, I am to going keep using erpprep for future certifications,
Ed.
SAP Activate 12
May 11 2020 - 23:01