Hello,
I guess you have checked "DST" (summer time), while it should be unchecked.
Please see image attached.
In premium version, you only input "Póvoa de Lanhoso" location and click "Search" button, the calculator does everything for you.
In free version, you can manually set: longitude, timezone and DST (summer time) and eventually you get the same calculation.
Póvoa de Lanhoso observed no summer time in Sep 1976, so with the DST option unchecked, you get 12:34 in bazi-calculator.com, just like on JLim's screenshot.
If you need some more details, you can have a look at the document about real solar time in bazi-calculator.com:
https://bazi-calculator.com/instr/RST.pdf