This worked for me with "Pinball FX3 Williams Pinball Volume 6 MULTi5-ElAmigos"! Thanks. It didn't work the first time I tried it, but it's because an account was linked in the settings (even though I never actually did that). Once I unlinked it, it worked fine.
English translation:
Backup the EXE
Find 45 F4 64 A3 00 00 00 00 8B F1 0F BE 86 F8 02 00 00 8D 9E F8 02 00 00 83 F8 07 0F 87 13 02 00 00 FF 24 in the EXE and replace 0F BE 86 F8 02 00 00 with B8 05 00 00 00 90 90. For me this was at offset 354B5A
Find 45 F4 64 A3 00 00 00 00 8B F9 8B 87 BC 00 00 00 83 F8 1F 0F 8F A7 03 00 00 0F 84 57 02 00 00 83 in the EXE and replace 8B 87 BC 00 00 00 with 31 C0 90 90 90 90. For me this was at offset 355A6A
After doing that, follow the steps in the original post:
Start Pinball FX3
Click the pinball table icon at the top
Enter any activation code. The game will hang with a looping sound
Press Alt+F4 to exit
Once you restart it, it should be activated