Is SIM network unlocking using app normal if phone simply expects a code?
Such unlock apps aren't official.

They employ various methods of unlocking based on the information they gather from the app installed and querying from supposedly authentic database of unlock codes. 

I have personally used an unlock service for an iPhone which was locked to a carrier. I needed to supply device information and within a few hours they reverted with the code, which worked. All at a pittance of $10. I chatted with them and they revealed their modus operandi. Official unlock codes are obtained (read stolen) from the carrier database and these operators pay to obtain these. Payment is done only after unlocking is successful.

Bottom line is that there is nothing official or expected in such methods. If it works, good, else ask for refund